I have no idea why ragu would leave, but I'm happy to speculate wildly.
My theory is that the Illuminati finally caught up to him, and he has to go underground for a few years. One day he'll show up again, and nothing will seem different, but you'll be able to rest easier knowing that the shadowy forces who would seize control of this world for themselves have been thwarted yet again.
He deleted thousands of strips on his way out
Don't hold me to this, but I think that deleted comics are really just "hidden" instead of removed from the database. If ragu decides he wants his comics back, he should ask Brad.
The what mentioned above is total fiction. Please don't take it seriously!