Getting Suggestions while installing Laravel through Composer
This is normal. Some packages can have suggestions but they are not necessary for your Laravel application. Those packages might be useful in some cases but for sure are not required to run or create Laravel application so you can safely ignore those messages.
I've just verified installing 5.5 version of framework and I'm getting the following list of suggestions:
symfony/var-dumper suggests installing ext-intl (To show region name in time zone dump)
symfony/var-dumper suggests installing ext-symfony_debug ()
symfony/routing suggests installing doctrine/annotations (For using the annotation loader)
symfony/routing suggests installing symfony/config (For using the all-in-one router or any loader)
symfony/routing suggests installing symfony/dependency-injection (For loading routes from a service)
symfony/routing suggests installing symfony/expression-language (For using expression matching)
symfony/routing suggests installing symfony/yaml (For using the YAML loader)
paragonie/random_compat suggests installing ext-libsodium (Provides a modern crypto API that can be used to generate random bytes.)
symfony/event-dispatcher suggests installing symfony/dependency-injection ()
symfony/http-kernel suggests installing symfony/browser-kit ()
symfony/http-kernel suggests installing symfony/config ()
symfony/http-kernel suggests installing symfony/dependency-injection ()
symfony/console suggests installing symfony/lock ()
egulias/email-validator suggests installing ext-intl (PHP Internationalization Libraries are required to use the SpoofChecking validation)
ramsey/uuid suggests installing ircmaxell/random-lib (Provides RandomLib for use with the RandomLibAdapter)
ramsey/uuid suggests installing ext-libsodium (Provides the PECL libsodium extension for use with the SodiumRandomGenerator)
ramsey/uuid suggests installing ext-uuid (Provides the PECL UUID extension for use with the PeclUuidTimeGenerator and PeclUuidRandomGenerator)
ramsey/uuid suggests installing moontoast/math (Provides support for converting UUID to 128-bit integer (in string form).)
ramsey/uuid suggests installing ramsey/uuid-doctrine (Allows the use of Ramsey\Uuid\Uuid as Doctrine field type.)
ramsey/uuid suggests installing ramsey/uuid-console (A console application for generating UUIDs with ramsey/uuid)
symfony/translation suggests installing symfony/config ()
symfony/translation suggests installing symfony/yaml ()
monolog/monolog suggests installing aws/aws-sdk-php (Allow sending log messages to AWS services like DynamoDB)
monolog/monolog suggests installing doctrine/couchdb (Allow sending log messages to a CouchDB server)
monolog/monolog suggests installing ext-amqp (Allow sending log messages to an AMQP server (1.0+ required))
monolog/monolog suggests installing ext-mongo (Allow sending log messages to a MongoDB server)
monolog/monolog suggests installing graylog2/gelf-php (Allow sending log messages to a GrayLog2 server)
monolog/monolog suggests installing mongodb/mongodb (Allow sending log messages to a MongoDB server via PHP Driver)
monolog/monolog suggests installing php-amqplib/php-amqplib (Allow sending log messages to an AMQP server using php-amqplib)
monolog/monolog suggests installing php-console/php-console (Allow sending log messages to Google Chrome)
monolog/monolog suggests installing rollbar/rollbar (Allow sending log messages to Rollbar)
monolog/monolog suggests installing ruflin/elastica (Allow sending log messages to an Elastic Search server)
monolog/monolog suggests installing sentry/sentry (Allow sending log messages to a Sentry server)
league/flysystem suggests installing league/flysystem-aws-s3-v2 (Allows you to use S3 storage with AWS SDK v2)
league/flysystem suggests installing league/flysystem-aws-s3-v3 (Allows you to use S3 storage with AWS SDK v3)
league/flysystem suggests installing league/flysystem-azure (Allows you to use Windows Azure Blob storage)
league/flysystem suggests installing league/flysystem-cached-adapter (Flysystem adapter decorator for metadata caching)
league/flysystem suggests installing league/flysystem-eventable-filesystem (Allows you to use EventableFilesystem)
league/flysystem suggests installing league/flysystem-rackspace (Allows you to use Rackspace Cloud Files)
league/flysystem suggests installing league/flysystem-sftp (Allows you to use SFTP server storage via phpseclib)
league/flysystem suggests installing league/flysystem-webdav (Allows you to use WebDAV storage)
league/flysystem suggests installing league/flysystem-ziparchive (Allows you to use ZipArchive adapter)
league/flysystem suggests installing spatie/flysystem-dropbox (Allows you to use Dropbox storage)
league/flysystem suggests installing srmklive/flysystem-dropbox-v2 (Allows you to use Dropbox storage for PHP 5 applications)
laravel/framework suggests installing aws/aws-sdk-php (Required to use the SQS queue driver and SES mail driver (~3.0).)
laravel/framework suggests installing doctrine/dbal (Required to rename columns and drop SQLite columns (~2.5).)
laravel/framework suggests installing ext-pcntl (Required to use all features of the queue worker.)
laravel/framework suggests installing ext-posix (Required to use all features of the queue worker.)
laravel/framework suggests installing guzzlehttp/guzzle (Required to use the Mailgun and Mandrill mail drivers and the ping methods on schedules (~6.0).)
laravel/framework suggests installing league/flysystem-aws-s3-v3 (Required to use the Flysystem S3 driver (~1.0).)
laravel/framework suggests installing league/flysystem-cached-adapter (Required to use Flysystem caching (~1.0).)
laravel/framework suggests installing league/flysystem-rackspace (Required to use the Flysystem Rackspace driver (~1.0).)
laravel/framework suggests installing nexmo/client (Required to use the Nexmo transport (~1.0).)
laravel/framework suggests installing pda/pheanstalk (Required to use the beanstalk queue driver (~3.0).)
laravel/framework suggests installing predis/predis (Required to use the redis cache and queue drivers (~1.0).)
laravel/framework suggests installing pusher/pusher-php-server (Required to use the Pusher broadcast driver (~3.0).)
laravel/framework suggests installing symfony/dom-crawler (Required to use most of the crawler integration testing tools (~3.3).)
laravel/framework suggests installing symfony/psr-http-message-bridge (Required to psr7 bridging features (~1.0).)
psy/psysh suggests installing ext-pcntl (Enabling the PCNTL extension makes PsySH a lot happier :))
psy/psysh suggests installing ext-posix (If you have PCNTL, you'll want the POSIX extension as well.)
psy/psysh suggests installing ext-pdo-sqlite (The doc command requires SQLite to work.)
psy/psysh suggests installing hoa/console (A pure PHP readline implementation. You'll want this if your PHP install doesn't already support readline or libedit.)
filp/whoops suggests installing whoops/soap (Formats errors as SOAP responses)
sebastian/global-state suggests installing ext-uopz (*)
phpunit/phpunit-mock-objects suggests installing ext-soap (*)
phpunit/php-code-coverage suggests installing ext-xdebug (^2.5.5)
phpunit/phpunit suggests installing phpunit/php-invoker (^1.1)
phpunit/phpunit suggests installing ext-xdebug (*)
and there is no problem with this installation. For example monolog/monolog suggests installing ext-mongo but obviously I don't want it and I don't need it so it's safe to ignore this suggestion, same for all the others.