It's a little inconvenient for someone setting up a new phone to have to wait a full day to install unregistered apps. But while I can't speak for others, it's a price I'm personally willing to pay to make the types of scams they mention much less effective. The perfect is the enemy of the good.
How would you feel about needing to wait 24 hours to visit an "unapproved" website on your phone? You would pay Google/Apple $25 to get whitelisted so people can browse to your personal website without getting a scary security message. This is the same thing since it applies to all apps, not just apps that need special permissions.
From the article I understood this to be a one-time delay, as opposed to having to go through the same waiting process for every single "unlicensed" app I want to install (which I would not accept). I'm just waiting 24 hours once to permanently change my device into a mode where I can install any app I like without any restrictions/delays whatsoever.