People are attracted to server-side programming because it simplifies the heck out of network communication. Instead of there being a problem in a network of finding where to send some data or message, a dedicated server taking on that role makes it clear where everything should go. Unfortunately, it creates some problems, too. It is now a single point of failure, so if the server goes down, everything goes down. If the server's hard drives crash, all the data is lost. If the server can't cope with the traffic load, then nothing works. You don't really eliminate the problem so much as exchange it for other, better problems.
Mokalus of Borg
PS - Personally, I've never been much of a fan.
PPS - But then, I cut my teeth on client-side software and dabbled in P2P networking back in the QBasic days, so I might be biased.