Previously if you were linked their videos it might have 1000 upvotes and 100,000 downvotes, and it would be obviously terrible. Now you just see 1000 upvotes and it would look like it has substantial support.

Google can and does remove videos they simply dislike by using nebulous policies against 'hate' or 'meanness' or similar. Removing dislike then, by and large, helps push those unpopular views that Google themselves approve of.

Does removing likes let them accomplish that? They can still remove videos that trigger them, but without a like count they can't push their ideology with the appearance of support.

I believe this is the actual reason why they will show upvotes but not downvotes, and as prediction I expect them to remove total views since that allows for estimating the viewer sentiment based on likes per view (or make it useless for estimation, for example replacing a count with big buckets like "thousands" or "millions").