Everyone feels insecure about their art at one time or another! And the reason most people procrastinate about their work and mistakes, is because you get those people who just can't help themselves to point it out.
I'd say that I'm a mediocre artist, and while I'm learning to get my character's anatomy right, I receive negative feedback from persons who draw nothing more than stick figures ~ and then I ask myself, "Who is the target market for art, and what makes one persons art better than another?" Why do hands HAVE to be the size of a persons face? Why is realistic art favored above abstract/stylized art?
Just because it is. I feel like individual artists who have distinct, unique artistic styles are often lost among the abyss of artists who all mimic a particular style because it's "popular". I prefer art that stands out from the crowd, opposed to art that looks exactly like someone else's.
I guess what I'm trying to say is ~ Regardless of your level of expertise, or the quality of your art, people will always find it amongst themselves to judge, criticize, pick-a-part and ridicule someone's hard work. They don't care how many hours you spent on it, or how many times it took you to perfect one tiny detail, or how frustrated you get when something just won't turn out the way you want it to ~ they only care about the end result and if it's pleasing to the eye. Being on DeviantArt has taught me that I can only please myself when it comes to my art, because there will always be someone, somewhere who doesn't like it, and will feel the need to tell me exactly why they don't.
Bright coloured, digital, realistic paintings are all the "fashion". I guess it comes down to who you are creating the art for ~ If you want to please the masses, you will have to find a way to give them what they want. Finding a balance would probably be one of the hardest tasks any artist would face ~ Trying to please everyone AND yourself is by far the most challenging thing, but I think that if you have the drive and the passion, you can definitely make it work!
You are extremely talented, and I think that you should have faith in your art and yourself and your ability to create the art you do. You are loved and followed by many people who respect you and appreciate your art, although unfortunately for DeviantArt, there aren't many willing to pay...
Sorry for the novel, and I wish you the best of luck in the future for your art, because everyone understands what's it like to doubt yourself and your abilities. Everyone compares themselves to others whom we deem to be "better" than ourselves. Instead we should be learning from them. But regardless, don't give up hope! You have the skills you do for a reason, you just have to let the world know that you're here!