Well Mac is known as the PC for designers (and professors). And each to their own, you should use whatever works for you.
As you can run either Windows or MediaMonkey through some form of virrtualization, the relatively small ammount of Mac users (as compared to PC) and that Mac and iTunes come from the same company I wonder how many MacMonkeys Ventis would be able to sell. After all it is an economics issue.
As a Windows user I prefer to think selfish on this issue and hope that they dedicate their time on making MediaMonkey better instead of porting it to other OS's.
The developers have indicated in the past that at the moment they weren't planning on a MediaMonkey for another OS, but that the option remained open for the future.
In the meanwhile we feel for the Mac (and Linux) community for not having their own MediaMonkey