If they're selling well, you would expect for at least some of them to be taken outside. If you just want something to check email and stuff like that, you're better off buying something that's used.
And yes, the fact that I'm not seeing them is a problem for them. Windows laptop manufacturers can get away with that because Windows is a commonly used OS and they're just competing with other Windows laptop manufacturers. Apple can't as much because they need people to know that they're product is being used. ChromeOS OTOH, isn't getting any attention and adding the Pixel isn't going to change that if it isn't clear that people are using it.
And yes, when tablets first came out they didn't fill any particular needs. Many years later, Apple figured out how to make them useful and convince people to pay for them. At which point many more uses came into existence. In large part because there was money to justify creating applications just for it. ChromeOS doesn't look to be going that way because nobody knows where these machines are or what they're doing.