I don't think it's at all clear cut and whilst I think that it's perfectly acceptable to make allowances for people's food preferences (reasonable or otherwise) I don't think it's acceptable to make allowances for bad manners.
If I ask people if there is anything they won't eat before hosting them I will respect what they tell me. If I do that and they still go "ugh" or make a face when something is put in front of them I feel I have their measure and yes I judge them on their lack of good grace.
I think it's interesting. We eat probably everything as a family and I am a skilled home cook, properly taught, with an understanding of food that goes way beyond a basic interest.
We have two children reared in the same stable and both pretty much grown up now. Their natural likes and dislikes are interesting:
DS: Pretty much anything but not keen on spicy food, mashed potatoes, root veg, mousse, (a texture thing I think), avocado, and has developed an intolerance to lactose. Absolutely loves casseroles and anything in a sauce - spag bol is meal of choice on return from uni.
DD: Has always eaten things like a chop, steak, fillet of plaice, vegetables, mash and mousse are big favourites, since the age of 4 (when a dinner lady put gravy on her cucumber and made her eat it) she has declined all sauces and gravies. We took this very gently because of the wide variety of foods she would eat. Gradually she started eating things in a white sauce: fish pie, chicken Veronique, macaroni cheese, carbonara, cauli cheese, etc.. Eventually, I realised when she was about 10/11 so very late that what she really didn't like was cooked tomato and that was why she refused pizza, spag bol, and other tomato based dishes. She still isn't keen on a casserole and pick out the meat and avoid the gravy but, and she's 16 now, she has recently started eating a dish if it comes with a jus or a light gravy or sauce and I am so pleased.
I have never ever forced or interfered with her food. I was only ever "picky" because my mother did that with me and sat there "eat this", "try this", poking her fork into my plate. It made meal times very stressful and I remember as a child sitting and be starving hungry but refusing food because it was the only way I could exert some control over her interference which actually went way beyond food.
And to cut to the chase - I am a recovered anorexic - the lowest my weight dropped was 7.8 in my 20s and I got a wake up call when I fainted and went to my GP and turned myself round with minimal support and not really many people actually knowing.
Food and eating are complex and are as much about external influences and love in my opinion and I can excuse people's fussiness or pickiness providing they are straightforward about it and don't criticise what everyone else is eating which is just bad manners.