Okay, so here's the thing with FFXIV. If there's no team or ranked play for duos and trios, it's pretty much down to luck. The skill ceiling isn't that high, so a lot of it hinges on whether your team can get it together and focus on the same target. And when you're playing with randoms, you never know if you're going to gain 100 points or lose them.
Now, about making the game solo-only: I think each class should get a bunch more abilities, make them trickier to play but also more rewarding for those who can handle it. And not just spamming damage skills, you know? We need something more creative.
For example.
Caster
They really should have a bunch of crowd control abilities like slowing, rooting, and stunning to help nail those kills easier. And man, I'd love to see interrupt mechanics like in WoW, though that might be a bit too much to ask for.
But the game will be a lot more fun. It will reward caster who can fake cast. And punish a caster who can't fake cast.
Healer
Instead of just buffing their healing powers (which would make them way too OP), why not give them more utility tools? Like, they could clear snares, stuns, slows from teammates, buff their speed and damage, blind enemies, maybe even knock them back. Just more support-style skills to make them feel more... supportive.
Tank
should be all about the frontline: super tanky, tough to take down, with a few crowd control skills to make them feel like real bruisers.
Melee
Should make melee a bit harder to play. Rewarding a melee who can find a good path. and punish melee who stupidity walk into target. (with caster buff , melee will have to play with more cautions.)
Range
It's fine for range. IMO
But overall, the game could seriously use more debuffs and crowd control effects. I'm talking slows, roots, stuns, fears, knockbacks, banishing... you name it. It would add so much more depth, making the game about smart setups and burst fights, not just non-stop damage.
Right now, the CC feels too much like PvE, where you're just whacking at anything that's have guard or purify.
The game should have more things to do. Track more CDs, Dispel friend's debuff , CC opponent more. It will make game more carriable for good skill player.