The animations have been worked, reworked and worked again and again. It stems from 1.0 when your didn't have enemy warning cones for their abilities (but you could still move out of the way) and much of 1.0 was standing in one spot (Such as MRD class gained a buff if they stood still for more than 15 seconds) and being animation locked. but since the enemy ability dodging became a core mechanic they opted for the loose, non-animation lock you have today

Again. 1.0 was a game that heavily and I mean HEAVILY relied on teamwork. You wanted to get a GC promotion? better go fight that big imperial machine, but bring a party first. Wanted your jobs AF body? better get an alliance.
The solo capability was added for (and focused on) the more casual players, so that people could progress with out needing a cadre of friends (like in XI).

Targeting with Tab works just as it did in XI, it cycles targets (if no target) from the left of your screen to the right.