First and foremost, you're comparing the story of an anime or manga to a browser game of all things, do you truly expect the same type of quality in story-telling that you get in the original source of the manga? That's like reading a novel instead of a manga and complaining there aren't enough pictures in it.

Additionally, on terms of the story itself you are forgetting that Oasisgames is a publisher and not a developer, and as a result they have had no actual involvement in the design of the story of Naruto Online, they license the game for use in several languages, but when it comes to the development itself they are but a tiny part within the whole creation system.

Also, while talking about the Gaara versus Deidara fight, correct me if I'm wrong (since it's been ages) but in the anime/manga Deidara DID in fact defeat Gaara, by threatening to * up the entire Sand village with one of his clay bombs, leaving Gaara to use nearly all his sand to soak in the blast, leaving himself defenseless for Deidara to take him down.

While one point I agree with is that in its current state the translation has quite some errors and issues, the team is aware of this and is working diligently to get them fixed.

But the key point remains: You're comparing a Browser Game to a Manga story, what is a bit of an odd thing to do. Not only do Browser Games usually have a more limited amount of resources available (in the end this isn't a Star Wars the Old Republic or Final Fantasy 14 where they got an entire department specialized in the story aspect of the game, an aspect that Oasisgames is not even involved with due to being publishers and not developers.) the act of changing the story itself would have much greater difficulties than simply opening a script and changing the text here or there.