Definitely agree that this is a problem (that is only going to get worse) ... as for the solution, I would much prefer they went through each class and reworked their low-mid level toolkits to:
1. Have at least a full rotation / combo, 1 AoE (healing or damage), and for tanks, healers, and specific dps, at least 1 utility by level 15.
This would give each class a 'basic kit' from the very first dungeon, and as such players could start learning the basics of their role from the very first dungeon. It also establishes a strong base for each class upon which future abilities can be added, and then integrated by the player as they level up and learn.
As an example, Lancer / Dragoon gets Impulse Drive (second combo starter) at level 6 and doesn't get Doom Spike (their first AoE) until level 40! Are you trying to confuse / bore new Lancer players SE?
It would be much smoother if by level 15 Lancer had at least:
True Thrust (first combo starter)
Vorpal Thrust (first combo mid)
Full Thrust (first combo finisher)
Heavy Thrust (damage boost and intro to positional)
Doom Spike (first AoE)
2. Give 'class changing' abilities as early as (sensibly) possible.
The main reason for this is so that, again, players can learn and integrate new abilities / class mechanics as they level ... as opposed to the current 'welcome to level cap, now re-learn your class' (and good luck on the dungeon speed runs).
An example of this is of course Dark Knight (The Blackest Night), which (for any of its other issues) would at least feel better in the 64-69 range and offer a smoother transition at 70 if it got TBN at 64 (2 levels after its first Blood spender) with Quietus and Bloodspiller (both important, but not nearly as class changing) pushed to 68 and 70.
And I won't even mention post 4.2 WAR, as Inner Release is just completely busted.
3. Group 'connected' abilities reasonably close together.
Again, learning, A connects to B.
Take SAMs Third Eye as an example... currently given at level 6, it isn't really useful until you get Merciful Eyes at 58! That's 52 levels to completely forget about Third Eye before it becomes noticeably useful (gaining HP is infinitely more noticeable than taking 10% less damage for 1 attack).
Third Eye and Merciful Eyes really should both be given at the same level (probably in the 30s) so that players can learn how useful Third Eye can be as soon as they get it. Which is then re-enforced when players get Hissatsu: Seigan (which should probably be in the 50s).