You have every right to dislike the fact that Omniverse retconned/ignored many things UAF had established before. But, to be fair, I gotta say UAF did to OS the exact same OV did to UAF. Dwayne and co retconned almost everything Man of Action created from Original Series.
Jetray never even got an appearance, since derrick didn't like him. Check. Many classic aliens, like XLR8, Upgrade, Wildvine and Grey Matter never showed up in UAF.
Retconing Kevin's backstory? Check. Alien Force actually was the first show to retcon Kevin's entire past.
Changing histories and backgrounds of people? Check. Example: Kevin and Gwen became aliens in UAF, when they were not aliens in OS. (By the way, Cooper was supposed to be a mutant in OS too)
Getting rid of the something he didn't like it instead of finding a purpose for it? Check. Original Earth Plumbers gone, and replaced with the Intergalactic Plumbers.
So, unfortunately, changing things is a common mistake most writers do. That's why I agree with Man of Action recent interview that labeled all the Ben 10 sequel shows as 'reboots' too. It's best to think of each series as a separate continuity.