The anime dudes were stupid for starting the series before the manga ended, so they decided to end the story in their own way and the outcome wasn't the best possible.
Yeah, sadly that happens far too often I think..
So many manga that could've been superb anime adaptions, but which they decided would serve better as a revenue or whatever, with a few episodes following the main plot, just to end up with some weird ending hard to relate to the original story somehow.
I suppose I can't ask for too much as a fan, but if they practically exist thanks to our interest in being told a good story, that is, being entertained, then they'd better make some effort not to look like greedy sons of.. of.. Greedy parents! >o<!
Anyway, people are too hasty. We fall in love almost always with the original story and I dare say most would rather not have fillers if they could make the choice, OVAs being an exception.