I've played in the MLS loads (though admittedly not on FM17) and I'm like 90% sure there is a youth intake alongside the draft. The draft itself, however, will be largely shit; and the Supplemental draft might as well be skipped altogether. There was an expansion made a good few years ago that added a huge number of college leagues and teams, and the drafts were unbelievable. Sadly unless you want to go back to like FM12/13 it's not possible, as there hasn't been one released for the latest versions of the game. What might help a bit is at least downloading an xml that adds the NASL/USL (there are a couple on the SI forum). I don't know if that'd affect the drafts too much, if at all, but it'd mean more active teams producing regens I guess.
The MLS is a really great league to manage in, once you're familiar with the rules (and honestly, they're not actually that difficult to come to grips with. People exaggerate this). It's also a league SI have actually put some work into in recent years; things like improving the way transfers are handled, which really makes a big difference.
I'd love another MLS save, but after the expansion I played on FM12 (I have to bring this up whenever discussing managing in the MLS, it really was that good) I can't bring myself to play it without. @dalenichol will attest to Superdraft day being even more exciting than intake day.