It seems to me not to be too dependent on price, just humans. I have had some near perfect Spyderco's (Para 2's and Manix 2's) and some not so perfect, lock backs where the gap between the tang and the back spacer is uneven. Grinds that where really not too even at all from side to side. I would say I have had more issues with some of the Seki knives (when talking Spyderco) than the others in that regard.
For the most part I accept it unless it is something that readily stands out and bothers me, then obviously I send it back. Examples would be a poor fit or gap on a lock back, it looks like a loose tooth to me. Another example is a Boker Solingen knife I received where the pivot hole in the Micarta was really roughly drilled and the lock up was so early on the knife it wasn't safe. It was a $200 dollar plus knife, so I sent it back and it was replaced with one without these issues (although it did have some fine scratches that I was willing to overlook) I don't buy factory seconds of blems so I feel I have a right it there is a glaring issue to have it dealt with and so do the companies I buy from I believe because I have never had an issue with them repairing or replacing a knife.
All that said ... I don't know that this is a new a problem, there is always room for improvement at the QC end in any company and like I eluded to, its not like they tell us to take a flying leap. In my experience so far I have never had an issue where the company didn't fix the problem. Overall I think the value we receive today for money spent is fantastic and no, for really small issues I don't really get too tuned up, if I have to find the flaw with a loupe, I'm gonna let it go.