OF COURSE! Before I had really ever begun to read much about dinosaurs and ancient life in earnest as a child, I recognized that bird feet and theropod feet were no coincidence. BUT to the common masses (of which ah'm) when one says "dinosaur" they are speaking about the classic perception of them - instead of the "non-avian dinosaur" terminology of today. Sometimes, it makes it difficult to ask questions due to getting answers involving modern birds.
What should really have been done would have been to abandon the word Dinosauria and to make up a new term for the entire clade, birds included. But it's too late for that.
As for the length of the tail being used as the cut-off line, while noting the transitional forms, I'd say just use what is normal for today's birds - short 'n' stubby.
Define that. Then look at *Sinornis*, *Confuciusornis*, *Sapeornis* and think again.Then look at juvenile enantiornitheans and juvenile *Confuciusornis* and think once more...
I'm not saying it's impossible (Avebrevicauda got a definition in Dinosaurs of the Air after all), but it's not trivial.