YANBU, because by definition, the picky, fussy, annoying ones without valid issues are actually being unreasonable. YABU for being tautological though. 
It seems that most of the problem here is people who are insensitive to others, and inarticulate about their needs. Sometimes it's impossible to tell whether someone's being inarticulate about their need for attention and validation from others, or being inarticulate about their gut-wrenching dislike of the food, or being inarticulate about having sensory issues because they're totally unaware that their particular sensory or behavioural issue is not widespread.
Most people seem to cut someone some slack for a polite, articulate explanation of need, and most people roll their eyes at someone being babyish and grumpy, or shrieky and bitchy. But that could be the same person five years apart (having been diagnosed with ASD in between, and given the tools to deal with stressful situations in a productive way) - or five minutes apart (snapping because a jeering close relative is there grating on nerves; being calm and articulate when feeling autonomous).
Give someone the insight about their behaviour, and the tools to feel they can deal with it calmly, happily and without any problem; and voila, you've transformed them from a shrieky, rude, picky eater, to someone who has a completely valid point.
I say this as someone who will happily eat anything most of the time, but who has occasionally been fussy about things because I had no idea how nice they could be. The problem was me needing to acquire insight and perspective, but I thought I was right at the time. My mother is an ambitious but very poor cook, who has almost no sense of taste or texture of food, so she really honestly doesn't care and can't tell, when the pasta is burnt dry, or the mincemeat is cooked to the point of being gravel with water sloshing round the outside and some curious little red squares that used to be tomato, or the green vegies are cooked until they are grey mush... I used to refuse sausages as a child because I knew they were inedible... discovered aged 18 that they were delicious. I also remember going to an italian restaurant as a child and finding it hard to find anything on the menu because I knew I hated everything there... I was really really surprised when the tagliatelle was delicious!
NB - for those who dislike coriander, that's apparently some genetic thing to do with being insensitive to what other people are smelling, while also being sensitive to some of the tastes underneath.