I can actually see where it can improve security against scammers trying to scam elderly and non-tech savvy people.
- Scammer tries to get someone to install malware from their site
- Victim isn't familiar with sideloading, but scammer instructs them
- Victim hits the first time 24 hour block and has to restart and wait
- The restart alone breaks contact with the scammer, scam thwarted
For the rest of us that know our way around Android, it's just a one time annoyance, after completing all the steps to enable sideloading, you won't have to wait 24 hours anymore.