Morel will play plenty as a super-utility guy, which is where his performance last season dictates he should be. He was bad defensively everywhere he played and bad offensively for half the season, and he was never an elite prospect. I don't think you commit a critical position to him as an everyday player when there are better options available, and I don't think that's inconsistent with committing to young talent. When PCA - who is an elite prospect and plays outstanding defense - comes up, you can commit to letting him play through his struggles. Apples and oranges.
Well, to begin with, if you have a very athletic guy who was bad defensively everywhere he played, perhaps a super utility role is not the one for him.
More importantly...
If you only do that with your elite prospects, you'll get stuck in a cycle of paying free agent market prices for mostly past-their-prime veterans to be average (+/-) regulars. That is not a sustainable, long term strategy. You'll notice that the Dodgers and Astros, for example, don't do a lot of that.