Planes can be customized, and the baseline design is based on what the majority of airlines want.
It's the fault of airlines. Nitpicking is fine if you want to add more details but doesn't change that.
And taller people on average can reach more controls, not less.
For glasses, how often does that make them come off compared to any other random reason for incapacitation? And what if there's a strap trying to keep them on? Acting like this is the only risk factor in isolation is bad.
There's plenty of scope for customization, but generally not in changing the shape of the cockpit.
Airliners are good at fitting 99%+ of the population well. But, in the end, airliner cockpits have switches and indicators up "high" and stuff down low that has to be easily within reach, but also not crowd your movement. There's a lot of adjustability, but adjustability (seat rails, etc) has been causes of accidents.
If you're within 5'2 to 6'3, odds are you can easily clamber in, fit, reach all the controls. That's all that's required. Even if you're outside of that range it might be OK (there is a 4'11 787 captain out there...)
As to glasses, there's no problem with having poor vision if it can be corrected with lenses. Aviation is not perfectly inclusive or accommodating of every disability, but it's not needlessly restrictive, either.
It’s also not about “enough space” in the entire cockpit, it’s about the layouts of all of the controls and being able to reach them.
“Extra pair of glasses” is not a solution in severe turbulence where the plane drops 100ft in 1 second.