It isn't possible to change default shortcuts, which is accessibility problem.
I am sure that it is nuisance to a lot of people that would-be-convenient shortcut is missing, or existing one is easy to accidentally trigger. It boils down to not being able change the default shortcuts.
For lot of users this is much more than a mild nuisance, though, if they have disabilities which make it harder or impossible to use mouse or more cubersome shortcuts (for example pg-up/dn to go to next/previous picture, which is accessible only through FN-key on numerous (mostly laptop) keyboards.
For people with disabilities there is also much bigger chance of triggering various unwanted shortcuts. While those problems could be addressed one-by-one, I believe it would be much better solution to allow changing, and at the very least disabling, default shortcuts.