It's possible to raid in pvp gear but unless you're extremely lucky with your pve and pvp stats meshing or playing an off spec, like survival hunter or retribution paladin, going into any form of serious raiding is like going into a 2k rated arena match in your pve gear. You'll fail misserably.

It would've taken me ages to get ready for kara if I had to do it with the honor system back when we started raiding kara, but that was because everyone and their mother was doing 5man dungeon grinding. These days it's another story, and the avaibility of pvp gear is actually helping new guilds and late commers start raiding if anything.

Next season it'll be s2, and s2 is fairly decent - but at the time the next arena season arrive the game will be in a state where you'd be complete left behind if you were stuck in blues/s1. I think it's a marvelous system, because it ends the whole pre-burning crusade problem where some of us were wearing NAXX gear while others were wearing greens.

Equipment is not the point of raiding, obviously everyone likes getting it, but the reason we want it isn't to be better than anyone else, no, it's because it's the tool that lets you progress.

I play because I like the challenge, I like defeatining new content, but I also enjoy competing against other players - and I certainly don't want ot beat other players simply because I'm wearing much better equipment than they are.