Nanotech has become a buzzword that can refer to excellent research or crackpottery depending on what's desired by the speaker. I hope you're restricting your rant to the crackpottery. but tossing baby with bathwater is practically an Olympic sport around Slashdot.
On the other hand, we've long used a lot of chemistry of all sorts that we really don't understand.
Just because we're not likely to get full up assemblers in the short term hardly means that nothing good will come of what's broadly termed nanotech.