Anyone paying attention to the project for the past few years can see that MAME is moving more towards its own integrated frontend than supporting other peoples' frontends. MAME has never gone out of its way to cater to other peoples' frontends, and if anything it's moving even farther away from that direction now than it has been in the past.
I have no particularly strong opinion one way or another, so far be it from me to reject your idea, but I'm just informing you that it's going to be an uphill battle for you if your proposal starts from an argument of "let's cater to other peoples' frontends".
Your proposal itself essentially comes off as "the MAME team has no style, so let's abdicate any responsibility for style or presentation to people who, outside of qmc2, have shown no inclination to provide full support for all of MAME's features". It's a tough sell. What I would suggest instead is, if the current startup sequence is not "aesthetically pleasing" (for whatever that's worth, being subjective from person to person), that you suggest ways of making it more aesthetically pleasing, rather than the non-suggestion of "MAME's presentation sucks, so let's ensure it continues to suck by foisting responsibility off onto a frontend author".
