All those gears would just confuse me.

I have 3 goals for my geared bikes:
1-climb what hills present themselves.
2-breathe somewhat easily at times.
3-go like a scalded dog.

to do 1, I move the chain inward at the rear.
to do 2, I move the chain somewhere into the middle of the rear.
to do 3, I move it to the outside.

I'm not sure why I even have a left shifter 95% of the time.
I can tell you when I'm in climbing gear, and when I'm going fast.
In between, I would have to look.

6 is plenty in most cases, and the chains are cheaper.
I think a 6-speed STI would be a big seller.
RSX made a 6-sp STI, but I've only seen one.