Is all chat a problem?

lately all I see is people spewing negativity in all chat. I know it can be turned off, but it feels like most people keep it on like it's mandatory. Could someone remind me the pros and cons of having an all chat? All I can see is the negativity growing from it lately; I don't think I've read a single positive or helpful comment out of it in a month. I don't understand why it's still around. Has Riot ever thought of just removing it?

Would really like the pros of having it around, cons seem pretty obvious to me.