Currently to upgrade all packages in your profile, users have to resort to using regex:

nix profile upgrade '.*'

As described in #7962, using regex is counter-intuitive. You'll have to rely on quotes in most shells and .* isn't always clear for people what it does.

It would be nice if there was a more explicit way to upgrade all packages, like:

nix profile upgrade --all

Or, more implicitly:

nix profile upgrade