Making checkbox and radio labels clickable

No, there are no issues with that, but unfortunately this is one of the most ignored html tags. Agreed, this tag is extremely important for accessibility reasons and what is more when it comes to layouts for small devices such as mobiles, you can't live without this.

No reason other than laziness. <label>s are essential for accessibility, and are also pretty handy for those of us who have poor aim with our mouse clicks :)