Downtube shifters are lame. And thats coming from someone whose road bikes are all steel, actively owns and rides many vintage bikes, and refurbishes/sells vintage bikes.
- I ride 63-65cm frames and reaching down to shift is far. That's simply inconvenient.
- bar end shifters, as already mentioned, do everything you love about downtube, but are in a more convenient place. My touring bike has em and I can't see ever changing due to all your stated reasons AND because they are conveniently placed.
- Gevenalle shifters, what I use on my gravel bike, do everything you love about downtube shifters, but are on the brake levers for a more convenient location.
Downtube shifters arent making a comeback. They are less convenient than STI shifting and that alone will mean they stay a niche product.
I did chuckle at your solution to not being able to shift while standing because it doesnt solve the problem.
awesome that you ride faster than others. Go you. That has nothing to do with shifter style and everything to do with strength and endurance.
and I'm hesitant to believe downtube shifters shift faster than STIs. My hand going from the hoods down to the shifter and shifting does not seem faster than my hand staying where it is and my finger moving a lever.
but I haven't timed it because, you know, it isnt important.