If forum were truly dead then it would be overflowing with spam. We clean it up 2-3 times a week. But I do understand your question, and there are good answers.
Most of it has to do with the relationship between NWC (the studio) and 3DO (the publisher that owned them). The game was horribly rushed, but that just one aspect of a long answer. The short answer is that MM9 was never as popular as MM6-8, so it didn't develop the enduring fanbase. It would be possible to mod it, but that would be much more difficult than modding MM6-8 -- which has been done several times.
But several folks still make daily visits here and are willing to discuss various aspects of the game, so do stick around.