The lack of higher resolutions was an issue - it wasn't a nice experience to run productivity apps on the Amiga, and better graphics only came much later (and required a new Amiga). At that time my PC went from CGA, to Hercules, to VGA with the same motherboard. A machine as complex as the Amiga should have been more modular. That would have made Commodore able to match PC capabilities more easily while preserving hardware investments by the users. When you felt it was time to upgrade your A1000 to a 3000, you'd end up considering a PC as well.
Being a machine seen as primarily targeted at games didn't help justify the development of a rich software ecosystem for it, and porting from other platforms was difficult. If the Amiga managed to acquire a critical mass of software, either original or ports, the story could have been different. Maybe if the 3000UX were cheaper and ran Coherent rather that AT&T's Unix, it'd be enough to be a viable Unix-like workstation.