Mostly, I've come to realize (even for myself), that "can you do better?" mostly means you have no actual, valid argument to make.
Expanding on the architect comment above - the one I always use is, "one doesn't have to be a trained chef to know if you don't like the food."
I used to take criticism too personally too - still do, if i don't watch myself. If you put a lot of yourself into an illustration and somebody finds fault with it, it's easy to take it personally. You have to take a step back, listen to how the person is saying it, try to see objectively if they have a point...
Expanding on the architect comment above - the one I always use is, "one doesn't have to be a trained chef to know if you don't like the food."
I used to take criticism too personally too - still do, if i don't watch myself. If you put a lot of yourself into an illustration and somebody finds fault with it, it's easy to take it personally. You have to take a step back, listen to how the person is saying it, try to see objectively if they have a point...