I'm constantly amazed by the complaints I hear from other travelers. On one recent flight I was upgraded to first and sat next to a woman who grumbled about everything, the selection of beverages didn't suit her, she couldn't eat any of the snacks offered, etc. she made me want to tell her to shut up and bring something that suited her requirements
Now I will say that if something reaches a certain point I will complain but I'm an adult, I plan ahead and I don't expect the airline to cater to my specific needs. I expect them to get me from point A to B in a reasonable approximation of the ticket they sold me and for the TAs,GAs, and FAs to be courteous but beyond that.....