I think the problem has been the lack of surplus talent in the system, so these sorts of trades just made a thin system thinner.
Hopefully that is starting to change, if Muzzioti, Rojas, De La Cruz, Crawford, Boyd, Garcia keep progressing, in a year or two the Phillies can trade from a surplus of young OFs - that's when it makes more sense - you have a good sense of which prospects are more likely to help you, and can move a couple who are likely to be blocked.
Same if they can develop a critical mass of young pitchers - if you have a couple young starters blocked at Lehigh, you can get a good return for a kid dominating AAA with a 95+ FB even if you don't think he's going to beat out his teammate next spring - some other team will gamble on him.
As we've see with Marsh, having good young talent to trade can land you other good young talent at a position of need.