Absolutely. First of all, I wouldn't give anyone my thoughts of their work unless I was asked- I would think that's just proper manners; second, I strive to be objective about my criticism of the work, so I tend to be technical, and never personal. (I've never met anyone who personally attacked me when they're critiquing my art, but I'd probably ignore them for being petty and lacking in anything objective to say about my work.)

However, the thin skinned reactions amuse me, especially from teenagers who insist "It's their style." They tend to be fishing for compliments rather than wanting to learn anything. Now, you can easily forgive them for this and their lack of general perspective, because they don't know anything about the world and are a bunch of overdramatic little shits who never had to face someone so angry and red in the face for being unhappy with work done in a professional, real-world context.

Critiquing the art of someone who's mature takes a little nuance; I would think that a lot of artists who can't take criticism identify a lot with their artwork, so they view criticism of their work as criticism of them as a person. They probably do their art as a hobby- the best route, as always, is to be constructive, and to be supportive; if you do art commercially, you learn to develop a thick skin and some emotional distance from your work. This can turn you callous, which is unfortunate, but if people knew how competitive and saturated the art industry is, being told "Your art isn't that special" and having your portfolio constantly rejected by clients or employers is something you learn to deal with- for example, you can use it as an incentive to find a way to elevate your art and make it stand out. Another way to take this is to stop trying to please anyone and make art because it pleases you; if people don't like it, then that's their problem. (Maybe that's another way of being unable to take criticism, though. lol)