A benefit of installing using your system package manager is that you can rely on your distro to manage the security of the package. If you just `pip install` it, you need to personally watch for new security bugs and upgrade (or backport them to your current version, which is what e.g. Debian will do for you). You'd also need to do that for all of the dependencies.
Up to you if you trust your distro's security team, of course :). I trust mine.