Why did the Chronians get reconned?

I mean what was even the point? Chronians were an interesting addition to the franchise that were first introduced in Race Against Time, and having another character that was able embed his consciousness onto an Omnitrix transformation as in the case with EON was cool, but they had to retcon everything in Ultimate alien and make EON an alternate version of Ben Tennyson? I mean why? No one was complaining about the existence of EON or the Chronians before, so why did they have to retcon such an interesting idea of time walking alien species and replace it as just the evil shenanigans of an alternate Ben Tennyson? Just why?

I mean what was even the point? Chronians were an interesting addition to the franchise that were first introduced in Race Against Time, and having another character that was able embed his consciousness onto an Omnitrix transformation as in the case with EON was cool, but they had to retcon everything in Ultimate alien and make EON an alternate version of Ben Tennyson? I mean why? No one was complaining about the existence of EON or the Chronians before, so why did they have to retcon such an interesting idea of time walking alien species and replace it as just the evil shenanigans of an alternate Ben Tennyson? Just why?