I think it comes down to expectations vs. reality. People place high expectations on the food for a few reasons; price is a driving force for sure and also, the food and dining experiences have gotten so much attention in the recent years that there is this "amped up" perception that WDW is a dining mecca, and the ADR system has really amplified this. People log onto the ADR system 6 months in advance at the crack of dawn just to get reservations to some pretty mediocre restaurants. There are websites that provide services to scour the ADR system and notify you when you can book. It's nuts. So people go through all that and think to themselves "this place must be amazing!" It's caused hysteria that in most cases is unnecessary and unwarranted.
When it comes to QS, you shouldn't have very high expectations naturally but the food should at least be hot and fresh. The 1 credit TS meals probably suffer the most in terms of people's expectations. The prices are high for what you are getting and the food is mass produced. You can find some decent food at some of the 1 credit places but again, if you're going into it expecting more than average food and more than good service, you are most likely going to be disappointed. There are exceptions of course. The 2 credit TS signature meals, you are paying premium prices and many times you are outside of the parks, expectations are even higher and probably should be. I expect very good food and very good service at 2 credit TS meals. But even still, I don't place the same expectations on the 2 credit TS meals that I would if I were dining in a nice restaurant at home. I'm still at WDW after all.