Honestly what they need to do is just quit having half a dozen or more mechanics in raids nowadays. LFR has to be a dumbed down version of the actual raid, so if the actual boss has 5-6 abilities then the LFR boss tends to have at least 4 if they don't have all of them that just hit for less, but that doesn't solve the problem of the type of people who queue for LFR usually can't handle that many things going on. This is why Dark Shaman is such a terrible fight IMO, doubly so in LFR. There's what, 6 things going on at once (tank debuffs, slime geyser, slime adds, elemental wall, meteor, purple swirlies?) and it's no wonder LFR people can't deal with that.
It's going to be harsh but they need to just cap boss abilities at like 2-3 abilities per boss, and be done with it. Maybe you can add an extra one for heroic mode. Instead, they said they LIKE the idea of personal responsibility and with determination stacks (and other things in general) they can tune the bosses to be super complex because either you can drop to an easier mode or every time you wipe you get a damage/health buff. That's just piss poor encounter design IMO. I daresay the majority would be happy with fewer mechanics overall, in LFR and elsewhere and those who like lots of mechanics, well sorry but you're the minority here.