That isn't the defining characteristic, though [ETA: under the conventional understanding of the word, at least - apologies for appearing to ask you for clarification only to then argue with you about it]. There is already a word for that and it's called entitlement. What distinguishes an incel is the added belief that there is something wrong with people who have romantic or sexual preferences that the incel disagrees with (as long as the preference is limited to consenting adults).
Personally my main gripe is with the implication that a person, who simply wants someone with traits that the person doesn't have him/herself, is therefore entitled in a way that puts them in the wrong. To hopefully illustrate why that's weird: I tend to be romantically interested in those bleeding-heart optimist types even though my own philosophy is relatively pragmatic. I admire that characteristic in others but have no intention of adopting it myself. It isn't obvious that this fact, on its own, makes me an incel, even if optimism is more rare, desirable, or difficult to maintain.