I have plenty to do every week even if there aren't events; the last few events have given me so many characters to level up and gain aff items for, I could probably go for two (maybe even three!) weeks just playing catch-up.
Obviously, that's excessive, but for the majority of the playerbase (the ones who have not been playing from the Very Beginning), a few days (up to a week) of time where you're not feeling pressured to get the New Shiny would be nice. I'm not actually complaining because I can still slowly work on things in the meantime. I got Odette to 50CC55, and Sophie to 50CC32 or something like that so far (got very lucky on some SC rolls), but a few others I want to level are still languishing at level 1 and Sophie is not max-aff'd yet so I similarly would not complain about breaks (I am mostly disputing your assertion that there is "nothing to do" if there is no event going).
I'm taking full advantage of this being a star event to work on some of those things now that I finally hit 32* in it this morning.