The answer may depend on the size of your network.
For a smaller network (perhaps no AD or servers) then users very well might just connect directly to a printer via IP. In that small of a network, it may well be better to connect directly rather than using a shared printer off of another workstation, in case the workstation sharing the printer were to be suddenly turned off.
For a small/mid-size network (with Active Directory), I usually use the AD as the printer server, load printer drivers (32 and 64 bit) on it and have them listed in Active Directory.
For larger networks, you should consider separating the print server (or have multiple) from the Active Directory, but listing them in the Active Directory is still a good idea. See the other comment in the responses regarding ACLs and permissions, as well.
Using the print server lets you manage printers centrally (for printer job/queue management), and the more printers you have, the more you'll want a print server to manage them. Being able to go into the printer from a central management point and clear a stuck job, check printer status or something is helpful sometimes.
It's nice for users to be able to auto-download drivers from the print server when you're installing a printer for the first time. Having them listed in AD also makes them easy to find for client workstations/end user and allows you to give the printer a common user-friendly name.
An alternative to listing/using AD (or even a printer server at all) that allows you to at least keep printer naming simple is to use a local network DNS name mapped to the printer's IP (and set the IP in the printer to be static). It's not too hard for a user to find a printer, add a printer, or know what it is if it has a friendly or easy to identify name.
Unless you have an unusually high volume of print jobs or an unreliable print server, going through a print server shouldn't be an issue.
Sometimes (rarely), I do print direct via IP when I'm dealing with Linux or Mac systems, to avoid having to set up connectivity with Samba on them, although these days Samba on Linux/Mac works really well.
EDIT: Updated based on feedback from comments below.