All right, I admit it, I can mount no reasonable argument to support my objections to the particular bit of usage I'm concerned with in this blogpost, beyond the fact that I hate being told what to do, particularly by strangers, combined, perhaps, with the feeling that a variety of uninformed assumptions are being made about what I might actually want from life by the utterer of this modern greeting.
But let's get to the point: if you say this to me, I begin to rather hate you; each time I hear or read this exhortation, I loathe it slightly more; the idea that I exist in an age in which such things are considered normal appals me. In short, whenever anyone utters the word, 'Enjoy!', as they present me with something - whether it be food, a drink, something to read, a person they've introduced me to, a seat at the theatre, et cetera et cetera - every tiny skerrick of enjoyment is instantly and completely drained from that moment of my life.
Perhaps what most irritates me about 'Enjoy!' is its implication that the person who says it has the right to grant me any kind of permission, that they have any sort of authority over me. Give me my dinner or whatever it is you are employed to do. Do it efficiently, and I will appreciate your skill. Telling me I must take pleasure from whatever it is you're giving me is bossy and annoying and almost certain to banish whatever small pleasure I might otherwise have gained from the event