Personal loot translates to "let's add even more RNG in gear acquisition".
And the reason I know this is because of how WoW works. WoW uses personal loot with RNG determining loot drops for you. Problem is, the system also includes a good chance of you getting nothing (or in the case of WoW, gold). They threw in a reroll system that allows you to make additional rolls for loot on boss kills by adding these tokens you can farm on a weekly cap.
Say what you want about the current system, but at least something is guaranteed to drop. In a raid environment that goes through loot distribution and at the end someone is getting something (which is good enough for me). In dungeons, whatever drops is still useful, especially if you leveled multiple jobs (conversely, it can be traded for company seals).
All in all, it's a system where if you're lucky it works. And since I'm one of those people cursed with terrible RNG odds, I get shafted by systems like that more often than not. At least under the current system I can see a loot drop going to someone who might need it if I don't roll on it.
While also adding a good chance of you getting nothing. As I've said, at least under the current rules (in an organized group or raid), someone is getting something for the run.