Actually, I don't really think it would even dumb a game down, dj at full speed does require tons of skill to nail it, if you can do it good for you, but it would not be affected by that idea, because if you mistime, sure, you would dj, but not before running into a block you'd dj from, slowing you down as it would normally.
Clearly, DJ is hardly a concern, especially given that DJ scripts already exist since long ago.
My idea is - less steep learning curve for beginners, unchanged advanced movement. I do think such change would achieve just that.
Besides, it is client-side thing. Don't like it? You can turn it off. Except I've got to like it, even playing old way before - it is simply more convenient.