Each of the `Excellent xxx' response you give differs in two important hitches from the `Insecure xxx':

1) it requires much common context, understanding, experience.

Everybody will understand a ``this sucks'' response, regardless of the reasoning behind it being clear.

Understanding a, and building better solution on, an involved response requires common understanding, common experience, between the parties of communication. (What the heck is a 4/2 split? I dunno, honestly; this response only serves as a distraction to me at that very moment).

Lacking common experience is a communication barrier hard to climb, thus frustrating. It may be that very precise subjects (like computer science) provide for more such barriers, thus more frustration.

2) the ``This sucks'' response lets you vent anger. Now there are two conflicting theories about controlling strong emotions... ;-)