I think they're going to target immediate contributors as often as possible. I doubt they draft a QB - unless they just don't like the other options available.
To me, QB comes down to: 1) can you build an offense around him? 2) how does he stress the defense? 3) does he execute consistently enough for 1 and 2 to matter?
Most QB prospects don't have resounding positive answers across the three. For Milroe, it's all about 3. We have proof of concept in building around QB's with Milroe's skillset, and he stresses defenses in ways few QB's can. He's still picking up nuances and struggling with consistency, and it would have been great for him to get another year of college ball, but he's at a pretty good spot relative to his experience.
Imo his style of play would work best with bigger, more-physical receivers - WR's or TE's, but he can throw the snot out of the ball, so he could unlock something in the deep passing game with Waddle and if Hill is still on the roster. If Miami traded Hill and replaced him with idk, say, Tre Harris, I'd like the fit better.