I've seen more and more artists doing this kind of thing themselves lately. I think in the past artists were more upset with people making more successful versions of their songs just by speeding it up and found it would not be as intended if they released it like that themselves.

Plus, saturation is probably something to consider, if you make a sped up, a remix and whatever else for every single song you release your original, thought out pieces will get a little lost in the noise.