In my opinion, if you're discouraged from sharing your work just because you get an occasional, "this part seems a little boring" comment, then that's on you for being oversensitive. I mean, it would be one thing if people were giving scathing reviews, but generally the community here seems to be extremely encouraging and positive, even with their critiques.
I've always thought that being open to constructive criticism was one of the best ways to improve yourself. It's awfully hard to learn from your mistakes if nobody can point them out to you for fear of hurting your feelings, no matter how gently they present their viewpoint.
When I comment on a MOC, I try to pick out in equal proportion things that I really liked, and things that might be improved on or considered from a different angle. However, just because I tell you that I think it might have looked better if you had done *abc*, doesn't mean that you have to agree with me, and I certainly am not going to belabor the point if I'm told that the builder did it on purpose because they like it that way.
Bottom line for me is that, if you're posting stuff in an online forum that is comprised of your peers, you shouldn't do so with the expectation that nobody is allowed to say anything negative about it, especially when most people are so nice about it. Sure, I enjoy it when people compliment me on my MOCs, but I also appreciate it when people point out things that might be a bit better, because it helps me improve. If you only want people to say nice things and can't take an occasional friendly tip, then I recommend you stick to sending MOC pictures to your mom or showing off to 6-yr olds.