Basically I think this is very bad news for arcade preservation (because that's what MAME is about, if you didn't know, check out the source code and you'll get it, it's not about programming/emulating first, but about documentation and preservation of sometime dying systems). (sorry to burst everyone's bubble)
I disagree - the ports will not reduce interest in completing emulation, in fact just in the last couple of weeks x-rays were made of a SH-3 board to better understand how some of the components are hooked up. People who are into hardware emulation aren't doing it because they want to play the games, it works like climbing a mountain just because it's there.
Additionally this is more likely to be beneficial for preservation. Preservation is not people throwing down 1000 euros on rare games to play at home, preservation is a higher number of people safely shelving them and using them less often - remember that these have finite lifespans. I've seen two repeated failure types on SH3 games (Mushi onwards) already, both are driven by length of use and only one of them is fixable.
As someone who does actually own all of them I'd love it if I could play a port of Mushihimesama 1.5 instead of having to plug the PCB into the cab. I could enjoy the game for hours on end and not put additional mileage on the circuit board, not worry about power spikes, not worry about the PSU failing and taking the game with it, not worrying about the CRT exploding and feeding back down the video wires (I've seen this happen.... RIP Time Crisis 2) It's just logic.