LR-5 is mostly about the whole team handle things well, sure he does not do huge damage unless you don't interrupt his fireaoe but there are a lot of sources which could cause damage, if there are melee DPS it could get more difficult. It's no doubt harder than all of the Tier 1 HM and around the same level as Sav-Rak/Lorrick.
Sav Rak is not just about avoid damage, it has a very tight enrage timer at least since 1.5. Even Columi could get him to enrage sometimes, the gear requirement is even higher than Lorrick.
Overall, the 3 bosses are around the same level, just different mechanics and challenges.
If you already admit that the 3 bosses are on the same level, why the hell would someone in their sane mind choose to kill 2 bosses but leave the third alive, and EXPECT the drop of the 3rd boss to drop for them ANYWAY. This is just making no sense whatsoever. And btw in no Tier 1 HM FP will you get 3 Columi pieces and 1 Rakata piece, 1 rare pet, 1 rare speeder. It is a flashpoint that rewards the player quite well for what they do. Let's not ignore the 8 + 5 BH comms we get.
Oh, and your calls to nerfing this Flashpoint when it has already been nerfed is ridiculous. If you are struggling with it you better improvise.