Earlier quoted context omitted.
Why should I choose that over disabling Gatekeeper? Your way adds more steps but is not any safer for me.
If you forget to re-enable Gatekeeper, you're hosed. That's the big one - security-related process/workflow should be as idiotproof as possible.
Let's not exaggerate. Everyone got by perfectly well for years and years just using common sense about what to install. Gatekeeper is a welcome layer of defense but I doubt many experienced users would be "hosed" without it.