I can see why people would be against this, but I don't find having nine races being divided by three factions very appealing. If you're playing with friends and family with different preferences it's even harder to find common ground than two factions, but if players from different alliances can join the same guild (correct me if I'm wrong here; it's old news) I might be inclined to say remove PARIAA.
Because we've never seen the need to join one faction and stick to it in Elder Scrolls games before (with the exception of Stormcloaks and the Empire in Skyrim), it's quite jarring to suddenly require joining one of these three and stick with the choice throughout the rest of the game. This isn't like with Skyrim where if you join either one you don't have to do their quest chains and stick to specific areas, though you will have to report to certain bases and which side you choose will affect the game greatly. If you choose a faction, you have to stick with it until lv.50 or make a new character.
It only applies to those who pre-order anyway, so later down the line you'll see less and less of these cross-faction players. I won't let it bother me, and in fact, if I choose for my Dark Elf to be in any faction other than Ebonheart, I'll accept the RP abuse from it.