Why use a print server?
There are a few reasons, none of which may be especially compelling at your size, but they are important to larger organizations.
Driver version control. Since your clients will automatically download the proper driver from the print server, you can be sure that your organization is standardized on a "good" version of whatever drivers you use. There were a lot of "bad" versions of the HP UPD in the early days.
Driver deployment. Similar to the above, you don't need to mess with installing drivers on each computer, you simply install it on the server and are done with it.
Centralized control of print settings. If you just have a bunch of B&W LaserJets, this doesn't matter much, but once you get into the MFP territory with multiple trays, virtual printers, and Printer Mailboxes, you start to see the value of configuring these settings once on the server rather than at every workstation.
Auditing. In certain regulatory situations, you may need to keep a record of who printed from a specific tray. For example, I worked for an organization that certified medical professionals to practice medicine in the United States. Who could print to the certificate paper (safety paper) was tightly controlled, as that document is literally life changing to the person who receives it. A print server allows for retroactive compliance auditing, as well as the initial restriction on who can print.
You can be sure that only authorized users are printing where they should be. Almost all printers have the functionality to only accept print jobs from specific IPs. When using a print server, you can configure the printers to only accept jobs from your print server(s) and use Windows permissions on the printers to ensure that users from the Marketing department aren't constantly printing to Finance's printer. This doesn't happen in smaller environments, but in larger ones where departments are responsible for their own toner, this causes bloodshed.
You don't really need a print server in your situation, given the small number of printers you've described. You've justified it yourself. Nobody is forcing you to use one :)
But in general, people use print servers to streamline client deployment, offer central management and to ease print driver maintenance. It's all about scale.
Generally speaking, print servers are an act of kindness to those who manage your desktops. Printers can be mapped through group policy and/or added script-o-matically. You could pay someone to lay hands on 50 computers any time there's a change, but why?
Edit--What MDMarra said about driver versions. I've seen drivers crash Word, for example. You can send someone to lay hands on all those PCs, or you can update the driver on the server. Voila!