It's not just about google play services. Once manufacturers are free to custimize things as they want, why will they not want to install something like UC browser by default which may pay money. Similarly for a mobile assistant of their own. I know people who had mywebsearch as their default search engine and didn't want to change it to google as they didn't think their was any difference. Given that all of these are solid monetisation opportunities, why would any of them bother to install google apps? Not saying this is bad in itself, but the fragmentation is going to happen.