I can think of a few possible ways to go about PvE/PvP gearing discrepancy but removing Expertise altogether would be a very, very bad idea. We need to keep the gear gap in PvP artificially small. Can you imagine the havoc people would wreak with ~2500 main stat and ~1000 power against fresh 50s at 1200-1300 main stat and ~500 power? NPC mobs don't complain when they get one-shot. People do.
You think 15% bonus from recruit gear helps that much, especially considering you loose hp and other stats from tion (I also wasn't subbed when they decided to give full free sets of recruit/tion on lv.50, looks like a very weird move)?
The only real reasoning for exp from players is 1) pve crowd: "hey, I don't want pvpers in my fp/op, its not fair how they got their gear!!!" 2) pvp crowd: "hey, I don't want pve'ers in my pvp, its not fair how they got their gear!!!!" - both opinions are obviously stupid. And devs are like: "what a good idea, now those idiots have to grind for 2 sets instead of one artificially extending 'quality' endgame!"
Anyway I played TSW for the past several months which has no exclusive pvp stat on pvp gear and it works just fine, I can play both pvp and pve to get my gear and I haven't seen anybody complaining.