The only toddler I have who insists on being taken out of her highchair is the one with the independent trait. As soon as she goes in, she's waving at her parents to let her out. My other toddlers will be hungry sometimes, but usually not extremely hungry when they go into the highchair. I usually have no problems with keeping them in there. My Sims will sometimes get the action to take them out, but I cancel it in the queue. I like the highchairs because I like my families to eat together at the table.
@Cupid I agree, maybe it's the way I play, but I don't have too many issues with the highchair.