You know those little cards you can get at some establishments, allowing you to rate your customer experience, or the customer feedback forms that anyone who makes an order online will be familiar with? There's often a multiple choice format wherein you might grade the service, the quality of the goods purchased, etc.
Football clubs tend not to have such forms. The customer therefore uses a variety of other means to inform the management of their thoughts. Traditionally this takes the form of clapping, cheering, whistling, sign- and scarf- waving, singing/chanting and BOOING.
You're complaining about people expressing an opinion you don't like because other people might not like it either.
Straight to the point of the matter in the first sentence. If our players lack the strength of character to cope with jeering and booing, they're in the wrong profession. I'd gladly trade my income for theirs to be booed at for 90 minutes 2-3 times a week. I'd even allow the throwing of soft fruit and veg.