I agree with 1clou, the positional requirements for weaponskills (for all classes) make fights more dynamic imo. And it comes down to timing. (i.e. Garuda does Slipstream, which is conal, so the perfect time to dodge behind her and use Riot Blade. Ifrit goes into animation locks for plenty of his moves, when Coincounter is sitting on the floor after a swipe/swing, there's another opportunity. Miser... probably not lol)
I also agree.

If positional requirements are holding back melees from dealing the damage that they are supposed to relative to other classes/jobs, then that's more so a problem with content.

they should do the shield size thing like they did in XI where there were i think 6? sizes of shields, the smaller the size the more you blocked but the less damage it mitigated. so a size 1 shield might block 90% of the time but only mitigate 15% of the damage while a size 6 shield would block only 20% of the time but reduce damage by 75% or something like that
Something like that, and I liked it.