They can't be really creative due to limitations on how gear is made. For example you can't create a piece of gear that does:

Enhances Divine Veil Effect
Enhances Cover Effect
Enhances Succor Effect
Enhances Spirit Within Effect
Enmity + 30

All on one piece of gear, there's a limit to "slots" for stats and boosts a gear can have in an MMO either due to client limitations, server limitation or simply design of the gear system. Though I do see why people kind of make fun if those who cite immersion being ruined, it's pretty silly to say it'll ruin it when the fact I can change my profession by equipping a gem makes me a completely adapt Paladin..that already ruins immersion.