Regarding CVT's I don't think they are strong enough.
And as stated in the OP, I agree, I think 8 speeds are too much.
When manuals and autos were 4 speeds, having a 5 speed was a revelation. Then when 6 speed autos AND manuals came out, it made sense for better acceleration AND better gas mileage.
Then Mercedes (I think they were first) brought us the 7 speed auto.
Personally, I don't know of too many people who thought, "awesome, 7 speeds, that's going to make a HUGE difference and is welcomed."
Mercedes skipped 6 speeds. And there 7 speed autos DID improve performance and gas mileage in their vehicle line. But would it of improved performance and gas mileage if they would of gone from a 6 speed to a 7 speed? I'm not so convinced.
Lexus wanted to upstage MB by going to the 8 speed auto.
And I don't think I've read a single review of it, where testers were rejoicing over having 8 speeds. Quite the contrary, where they've felt it too much.
So too me, nobody has "rejoiced" adding additional gears since 6 speeds have become common.
It just makes for too many gears.
4 underdriven gears
1 slightly overdriven gear (.90)
1 significantly overdriven gear (like .75) for highway crusing
I personally think that's perfect.
So IF I was to of had a say in the new ZF 8 speed auto, I would of made ALL the advancements they made with it, and all the robustness of it, and made it a new 7 speed auto AT MOST, and possibly just made it a better 6 speed auto. And in doing so, they probably could of made it 20-30 lbs lighter (since they made the new 8 speed the same weight of the current 6 speed).