I have no problem with people selling for a profit. Seriously, aside from warm fuzzy glows and a dedication to retrogaming, what do you expect to motivate people? People put a lot of effort into these things, and typically their return is something much less than 50 cents per hour invested, unless they really do sell 15000 per month. If you don't like the price then don't buy it. I don't see the costs as being outrageous compared to, say, buying a PC+video card to run CRTEMU/Groovymame.
Innovation will drive prices down over time, and eventually all of our Mister gear will be obsolete anyway so just grin and bear it.
I like the consolized Mister Multisystem for what is is. In some ways it is cheaper and prettier than the vanilla Mister, has some cool features, but then it is less customisable or upgradeable. I think it would appeal to some people, especially those more concerned with enjoying the capabilities NOW vs 5 years in the future.
In terms of Mistercade, I'd still prefer that as a dedicated solution for an arcade cabinet. It is made for a purpose, and that is what I want to use it for. Some of my preference comes down to things being natively incorporated (like the JAMMA interface, volume etc.) and the form-factor. Less "accessories" required (IO/USB/JAMMA boards) compared to any other options. I see a better upgrade path for it too.