If you separate the two... that means the tables that don't want to use feats will be getting twice as many ASIs as they do right now by needing to use the "ASI feat" in all the feat slots they are now getting... plus then the straight ASIs. Maybe some tables would be okay with seeing PC ability scores grow doubly like that than they do in the 2014 game... but I would have to imagine that's not exactly what a lot of people are looking for either?
More feat slots, or splitting feats and ASIs just mean more locations where non-feat-using tables have to fill up with additional ASIs. Do that too much and those tables are going to have their primary 2 or more ability scores maxed at 20 fairly quickly. Which might be okay for some... but that's definitely something WotC will need to survey on to see if that's the kind of thing most tables actually want.