The Mac Mini hasn't really been touched since 2014. Now Apple has brought the Mac Mini into 2018.
The MacBook Air hasn't really been touched since 2015 except for a little spec bump in 2017. Now Apple has brought the MacBook Air into 2018.
I have had my 500GB MacBook Pro for almost a year and it't filling up quickly, and it't time too offload some files. But to where? That's how and why I got a new, but used, computer.