Why the hell do we need to play a new champ to earn a hextech chest?

So, every 6-7 days, we get a new hextech chest. The ONLY way to get that chest is by playing a new champion and get an S- or above. Here's the problem, why do I have to play a new fking champion.

I want to play my main, not to play Urgot just to get a hextech chest. It's honestly really annoying.