Sure, but this strikes me as naïve. It can take less than being nefarious to get booted off of a service (like having an Apple developer ID) like having a corporation or government agency filing a potentially unfounded complaint against you (as we've seen with YouTube videos and, this very week, Jotform's Web site.)
The problem I have with Gatekeeper isn't in the pleasant, straightforward scenario Apple wraps into its copy. The problem is giving a corporation direct control over whose apps can and cannot work on a computer by default is a set up for some depressing abuse stories that can only be rectified by turning off security or performing UI acrobatics.