Ah, but see, how many versions of MS Word would we get if we received it (and support like Karen's) for free for 24 years? Some folks might not realize that almost everyone in SIL receives no salary, but instead we raise our own funds to give you Toolbox and FLEx for free. Even our office space and equipment comes from the funds we individually raise. We don't get grants (though we try and are still trying!) That would be my answer to your question: if only we had 1/1000th of the resources that the Microsoft Word team has to work with, that'd be great!
Since this seems to be point of contention after almost 20 years, perhaps it would help the healing if I say a few words about what we were thinking in introducing FLEx with a more constrained model? In essence, we did not see how we could provide all the features of FLEx without having a baked in model, and we needed those features to empower a much wider range of people in working on dictionaries and texts, collaboratively. We knew that this trade off between flexibility and capability was one that would not suit many people. And that's OK; there is a reason we have MS Word, Adobe InDesign, LaTeX, etc.
Note, I'm not saying that we could not have built FLEx on top of SFM. We just did not see how to do it at the time, with the resources we had.
On the subject of conversion: One of the beauties of Toolbox is that you "bring your own model". While this is very powerful, it makes
automatic conversation to some other model impossible, because the semantics of your model are not encoded in your database. There is no way for the converter to know what maps to what. To help with this, we have built many tools. Consider
SOLID, which allows you to add some semantics to your SFM model. SOLID can use that information to both do some structural checking for you or, if you want to convert, can then interpret your SFM and move it to LIFT/FLEx. I would guess that thousands of people have used various SIL tools to migrate, so it's not as if we abandoned SFM. If you've found that SOLID cannot be taught your model, and if also our (free) conversion experts have thrown up their hands, then that's testament to Toolbox's enduring flexibility, not our indifference to your needs.
Jokes about FLEx's ironic name (for which I take the blame) are always welcome :-)