On the topic of Hybrids. I am actually against them.
As in WOW it created a situation where honestly everyone was DPS no one wanted to CC, Tank, or Heal.
Tanks and to some extent Healers are rare enough as is currently allow them the option to go pure dps and I don't even want to think about Queue times.

IMO if you're going to allow hybrids/everyone the option to DPS you might as well just let us be self-sufficient.
Atleast then you can still group/go through content.

Seeing as MMORPGs are about playing together there should be group content. Just being self-sufficient would not imo "kill" group content. But I feel it might redufe the ire and toxicity that seems to be flowing from group content.
My issues with the Trinity system is that it turns into the blame game, and folks seem/tend to dislike the role their favorite class/job is given.

That said Trinity often creates a balanced gameplay system.
I have not played GW2 (which I hear does not use the Trinity System.) I wonder how combat works there.