Plus there's stuff like Cave PCBs which, certainly last time I was on AO or KillerCabs (alas no more), they were incredibly popular and still being made. I am a little out of date though.
The problem with Mame cabs (IMO only) is that as great as the emulation is these days, it's never as good as the real thing. No matter how much people will argue otherwise, for me, it can't beat it.
I built a mame cab myself once and it was really nicely done in a superb little Subelectro cabaret but what ultimately killed it for me was the ability to have 1000's of games on tap. It became instantly boring.
But then I'm a bit like that. If I'm at a show like the Slam then I tend to wonder about and get bored and don't necessarily play many of the games (though I did play the vids a bit this time). If I'm at a small meet with a dozen cabs you tend to get drawn into getting into them a lot more. Much more fun.
Quantity != Quality IMO.