What you’re asking is the equivalent of “Why can’t I just press a button and have a plane takeoff, fly, and land by itself”. You can have a plane that does that, but only in a limited context. To program the whole decision tree for all cases is not economical (or feasible?).

ffmpeg does all things media conversion. If you don’t want to learn how to use it, you find someone that does (or do the LLM gamble) or try to find a wrapper that have a simpler interface and hope the limited feature set encompasses your use cases.

A cli tool can be extremely versatile. GUI is full of accidental complexities, so unless your selling point is intuitiveness, it’s just extra work.