That happens. You buy bike, ride it a while and find out that it has some fatal flaws. Definitely sell it. Why ride a bike you don't like? If I were you I would use you're hard earned knowledge of what you don't like in a bike to go out and get a new bike that captures all the best qualities of your older bike, has all the new fun features of a modern bike and has none of the qualities you didn't like in the bike you just got rid of.
By the time you have your fourth bike or so you should be getting close to the perfect bike for you.