ignoring the old-timey nostalgia for mechanical stuff...
1. comparing like to like, they don't seem to be. for both ultegra and di2, mechanical appears to be 120-150g heavier. i'm sure there are cases where it goes the other way, but it's hardly clear cut.
2. "hard to know if you've changed gear" !?! what!? i have never experienced this, gloves or not. electronic shifting isn't totally silent, and there's the button itself, and the fact of it getting harder/easier to pedal.
3. true. not sure that'll hold over time, depends if the same forces that generally make electric things cheaper than mechanical ones will apply here
4. the "problem" is that the batteries last a long time? all things require maintenance of some sort, the electronic drivetrain requires a plug-in/charge at some interval, which is likely far less than some other things like chain cleaning, air in the tires, etc. are those also huge problems?
5. i'm a lousy mechanic, and i can't/won't replace drivetrain cable or re-index/adjust a derailleur. had to take it in to do so many times on my GRX bikes. never had to on Di2. so, a bit of maintenance vs... NONE. i get that it's nice for things to be "easy" to maintain, but eliminating that maintenance (no cable to wear out) is better.
2 out of our four bikes are mechanical derailleurs. i will not buy another bike with mechanical shifting.