I find this a strange opinion...
1) Competition is always good, especially for you and me the consumers, and drives quality/specs up and prices down.
2) It's up to the OEMs to up their game. Google/amazon etc may be huge, but so are Samsung and Sony etc. Do you honestly believe google could drive them all out of such a huge globally lucrative segment when it's not even their main line of business?! It's like worrying that the Cooperative is going to drive Tesco and Sainsbury's out of business because they can undercut them with their cooperative practices...
3) Even if I agreed with you in principle, the high upfront cost of unlocked phones rules them out for the majority of consumers who prefer to buy contract phones with few/no fees upfront (despite possibly higher long term costs).