You made good points, but I think being human is seeing the reactions of your peers directly in their faces as you say something. Likes are an approximation of that, but I don't know if it gets close enough to be worth all the drawbacks.

But to be honest the nastier part is probably the notifications stuff always calling you to see that some random person you don't even know or value has clicked a button.

Another issue is that a like from someone that only likes things they actually do like should be worth more than a like from these crazies that just keep liking everything they see, but there is no real way to measure this -- while in the real life we can often tell fake likes from real likes.