I personally think the EXP gains in general for PVP modes specifically should be increased. In a game founded on the basis of/owes its success to the PVP aspect and not quest, the amount you get from killing is abysmal in comparison. It's a little ironic that the entire first page in the EXP category are all questers.
Either way, for the exp as a function of playercount, I do agree, I don't see why that should be a factor.
However, for elo, I can understand why having more players in the room, and also having a longer kill-streak contributes to higher elo gains. It's harder to continue winning against a larger amount of opponents and is a good way to balance out fighting the same person 30 times in a row for less elo gain.
