I'll first say I have a Roku that I use more often, just because.
That being said, what I do use my Chromecast for is watching stuff from the CBS app. It's not the All Access CBS, just the regular one. They stream a lot of stuff there but it's not available on Roku so Chromecast to the rescue! I do use it for my YouTube TV, Netflix, MLB, NHL etc., the darn little thing comes in handy!