People from Google know about it (at least those who work on fixing Android) - I reported the security hole that AdBlock uses (that allows it to set proxy to all apps without root) and they've set high priority to it. The AdBlock Plus guys (I have nothing against them, I use adBlock myself all the time) even commented how it could be solved on the reported issue.

I don't think it's a problem to us - people who block ads, don't click on ads (speaking from my own experience). But I might be wrong - if the installation rate of adBlock gets really high (like 10% of devices), it could be a problem. There were already numerous applications like that already though - the only difference is that AdBlock works without root - but it is because of a HUGE security hole (imagine: it could be used for pishing or spying by any app!).