One other things I'll note that I haven't seen mentioned yet is that DKP or some type of currency based bidding helps maximize utility from drops by ensuring that people who value something more get it over people who value something less.
For example, I have a
https://wiki.project1999.com/Shadow_Fang_Necklace . Aegis rarely gets NToV kills, but they do trickle in from ban weeks and other things. If we killed Aaryonar and got
https://wiki.project1999.com/Amulet_of_the_Dreadgazer it is definitely an upgrade for me, but it is relatively minor; I have a number of slots that are much more in need of a substantial upgrade. If we're all rolling need, than I'm rolling on that. But I'm not likely to pay more than about 30 RAP (Aegis DKP, roughly equivalent to hours of raid attendance) for that, and someone else is almost certainly going to value it higher, which means it goes to them. That's good, you want things to go where they are higher impact.
Likewise, if there's a
https://wiki.project1999.com/Vyemm's_Fang dropped, I don't want a Shadow Knight or Bard rolling on it because its a AC/resist piece or they're level 54 and don't have a better weapon yet. SKs can trivially get a stronger weapon, while that Fang is a top tier Rogue piece from a very hard and contested mob. That naturally fixes itself with DKP because the Rogues will bid it up way higher than Bards or SKs will be willing to pay.
You can try and work around this with a bunch of rules about who is allowed to roll on what, but some type of currency works better since it naturally adjusts and takes into account personal preference instead of what people think you should be getting.
One thing I have come to realize though is that no matter what method you use to allocate loot, some people are going to be unhappy about it.