I think a few things about this issue. None of them really good tbh.
First off, I do not understand the decision to have the gap in leveling chance and level you complete.?! Why. Logically the chance should diminish when you try to level ABOVE THE GRIFT YOU JUST COMPLETED not 9 levels BELOW.
The time invested in a gem level for augment becomes more and more daunting as our power creep allows us to push further up the grift ladder. To just level a gem from 0-70 in empowered grifts it requires MINIMUM of 18 grifts. Of course unless you are doing level 80 grifts at the end you will have some failures so then we are talking more like 24-25 Grifts. This requires approximately 16-20 rifts (guesstimating key drop chance off the top of my head) The gold cost I cannot include here tho it can be sizable as it would depend on where and when you decided to raise your grift level. The cost of the 3 *uber gem to cube the augment. This is just to level it to 70 for augment, keeping in mind that most ppl do push their augments further and further and with power creep arriving they will need to REDO their augments from zero through ... 85? 90? 100?
I saw some comments regarding gear augmenting. That this is considered an extra that is not required and is only for people who want to push ladders. I don't believe this is a fair assessment. Gem leveling and augmenting is now an integral part of how this game functions along with Paragons. And saying that gem augmenting nullifies Paragons is not really accurate. In order to fully augment a set of Ancient gear to even just 70 that is 13 gems. That comes along with a significant amount of exp which = paragon which = main stat and so on and so on.
It really starts to look like Blizzard making "busywork" for players. No quality of life in this type of system especially since it all gets thrown away once the power creep allows higher grifting / gem leveling.
I understand that time invested = payoff in all the ways. Acquiring and Perfecting gear stats (tho less of this since augmented gear has a HUGE time investment and people become less likely to swap out gear unless the item is SIGNIFICANTLY better) Acquiring Paragon (still has value as it equals one augment gem level that doesn't go away) However, I DO believe there is some point at which this system needs to grow along with the power creep. The empowered grift did start this process but it is NOT enough.
I don't claim to have the solution. But anyone who plays knows that the problems do exist.
I can throw out some ideas that are not necessarily thought through but i will toss them out here anyway.
Increase amount of chances you can level in a grift.
Create an achievement that would allow you to start your gem level at 35 (dumb and fraught with problems i know)
Ability to BUY your way up a gem to lvl 35.
Ability to salvage an augment and retain 50% of its value (if it was 70 it will be 35 when u salvage it)
Allow leveling chances to retain 100% up to the level grift you just completed. with a 25% decrease each level above it. (Completed a 70 grift. 75% chance to level gem to 71. 50% chance on 72 etc.) Or 50% each level above. so you can only possibly do one above.
I know these ideas are not fleshed out and don't take into account the big picture that Blizzard is "supposed" to take when making long term changes.