The PoE elemental weapons only drop from 35 PoE and aren't available to PvP-only players. Nor are any of the PoE weapons, but whatever.
I mean, PvP players have always been locked out of some of the most desirable gear. Including pure progression, actually. Now there's quite a bit of desirable gear. I am personally surprised at how reasonable some of the sweet ToO goods actually are to obtain for a player of average skill.
While I can sympathize to a degree with the idea of gear being "locked" behind one mode or the other, the truth is that it is an effective motivator to play each modes for those players that participate in both. For a player like me, that plays both but neither in a particularly hardcore way, it feels about right to have desirable goals that can only be obtained in each mode. I would wager that a majority of Destiny players are actually in this group.
I was thinking this at first (Combustion on Golden Gun), but people really haven't been clumping. Staying near but NOT tightly together seems best, or even having two stay near one another and the third flank wildly.