I don't think that making such engine requires amazingly large amount of work. You don't have to come up with Football Manager like simulation from the start. Just make some crappy optional one, and update it gradually. That's still better than what most games have.
By the way, there was Football Manager Live with both 2D and 3D engines. Game was pay-to-play and despite the popularity of the whole game series, this one still died.
I think the difference is that in HT and BB, the result of the play is determined by random numbers and then an appropriate bit of text to describe it is pulled up - so any visual representation of an engine would have to just pull from an animation that matches the result, rather than how SI does it with FM, where the player skills and decisions determine the movement of the players and the ball.
And yeah, FM Live was dying out at about the same time as HT Open (I think that's what it was called) launched. I kind of think that if SI can't make it work with their staff, it's probably not possible, even though I do wish they'd given the NHL:EHM franchise a little time.