Access was kind of amazing, but it had a critical "flaw" for getting really accepted back in the late nineties: Changes were instant.
In the current world of autosave-everything, that wouldn't be a problem, but against a backdrop of "Nothing is permanent until you hit ctrl+s", it was a complete headfuck to suddenly be unable to back out your changes because you accidentally typed something into the wrong cell.
There were lots of other issues with Access too, but I think that aspect was key to it being daunting and off-putting.
If someone sent you an excel file, you'd feel comfortable trying things and playing around with it. If you really needed, you could copy a sheet and easily make changes without fear.
If someone sent you an access file, you'd be scared of making changes you couldn't back out of. When you don't enable experimentation, it's hard for users to get to grips with unfamiliar software.