Inappropriate mount? What mount would you have put on it? I'm assuming that by "Professional", you mean it should have had a PL mount? I don't think that would have been a good idea. Have you priced PL lenses? Plus, that would put it squarely in a "Professionals only" box and I don't think it wouldn't be able to back that up with the rest of the expectations that come with that claim. Maybe you meant the opposite and that it should have been meant MFT?
The whole point of the BMCC is to put professional image quality in a package that indy filmmakers could afford. It was never to make a camera that would compete head to head with Alexa and Red. It's for people who are on a tight (or no) budget. So, then the question is, what mount is the most popular, widely available and has the most options available for it? Well, that would have to be Canon right? What camera currently is used the most by indy filmmakers? It's Canon right? Some may argue that it's Panasonic now and to this we see the MFT mount version pop up. But otherwise, I think it's safe to assume that the people who would be first to buy this camera probably have a lot of EF glass already. Right? Also keep in mind that there are a ton of popular lens mounts can be adapted to EF too. Olympus, Pentax, Minolta, Nikon, etc. So you really are not that restricted to began with. The biggest restriction seems to be at the wide end but as we've seen, there are options out there. And, the situation would really be no better with PL mount.
The thing that I think both sides of this argument have lost sight of is that the BMCC is not made for everyone. It was made with a particular user in mind. Indy filmmakers stepping up from DSLRs. Pros will want more from their camera systems and will appropriately choose to shoot on a camera that better suits their needs. Shooting a commercial with a high profile client? You're probably just going to rend a RED, a set of PL primes and shoot 4k RAW. But that's not what this camera was intended for. Can you use it for that? I'm sure you could! But with so much money involved in commercials and so much riding on a single day of shooting, I can't imagine it being the best decision. If you've ever worked on a big budget commercial shoot (and I have) You'll know that the choice of camera isn't always made based on price. The camera needs to offer such fine grained control that's just not there on this camera. But I don't think you can fault them for any of that because like I said, It's not intended for that kind of situation. I'm sure there will be a lot of crossover though. The more comfortable people get with the camera and the better the firmware gets, I'm sure we'll see more and more professionals using it for those quick jobs with less riding on it.
Where this camera will really sing though is in the hands of talented and motivated indy filmmakers who only care about getting the highest image quality and are willing to sacrifice a few niceties in the process. So yeah, a lot of the people in this forum actually. ;-)
As far as resale value goes, only time will tell. If the next version comes out too soon then yes, I think a lot of people will be upset so I do think you're earlier point is valid. I hope they will wait at least a year before announcing anything new. But I have a feeling that even after a super 35 version (or whatever) comes out in a year or so, the original will still be a desirable camera with indy shooters. Similar to how the GH2 is still popular. The price will obviously come down a lot (maybe in the $1500-$2000 but that depends on how much the next version costs) but that might actually serve to make the camera even more desirable to indy shooters making low to no budget films. And just imagine, by then the firmware will have matured computers will be faster and SSD media will be even cheaper!
My point is just this: The BMCC is not for everyone. If it doesn't suit you, then it doesn't suite you and that's fine.