I agree. This is a very sensible suggestion.

There is a lore reason why TBN is given to you after completing the level 70 quest. Even still, they could just as easily give you a 15% self-only shield at level 10, call it something else using their standard naming convention ("Edge of Black Bubble of Darkness") and then upgrade it to "The Blackest Night" at 70. You can see that the dev team is trying to do this to an extent with some abilities (Inner Beast -> Fell Cleave), but their entire four person dev team is probably allocated to designing new dps jobs for the next two expansions, such that there will be a steady supply of new players to buy Mogstation glamours in the future. So I'm not holding my breath for any sort of intelligent job restructuring.

There are plenty of other things that they should implement but haven't. You should be able to apply glamours to change action animations, rather than throwing away animations that were used in defunct animations or trying to make them into poses. I'm sure there are plenty of DRKs who would have liked to use Shadowskin's animation for Rampart or even use HW's Delirium animation in place of Souleater. I'm sure that crafters would love to sell you the chance to change around your Shadow/Egi/Faerie to a more cosmetically appealing form. Talent trees are likewise another way to maintain older abilities in the game while preventing button bloat. None of these are original ideas, by the way. You just need to look at what your competition is doing better than you and steal it.