Interesting bug, you can trap creeps as long as there is a path from entrance to exit (the game doesn't check if individual creeps have a clear path to exit.)
If people don't like tower defense games, why do they even come to the page to comment? You act like someone making another tower defense games takes away from your enjoyment of other games somehow. Many people do enjoy them, as evidenced by the high ratings that TD games generally get on this site. If you don't like the genre, then don't play the games, its that simple.