I'll play devils advocate and say they do have their place.
Our V4's are rather complex machines. Not completely unserviceable, but certainly a harder bike to work on (My old i4 carbed Katana was easier!). If you disagree, take off those V4 throttle bodies and have fun putting them back on & plugging everything back in. 😭
P-twins are SO simple for maintenance. Super approachable to new wrencher/riders, less parts overall (fewer cylinders, duh), and parts availability/compatibility from using the same engine in many chassis (eg, R7 vs MT07 ; Rebel 500 vs CB500F)
... but do not forget there are dope AF P-twins!! The KTM 890 Duke "Super Scalpel" being a glorious example of a thrilling P-twin. (I have a crawler on eBay awaiting for someone to sell their Brembo adjustable brake master cylinder next time one goes down...)
There's more points i can make about weight, COST (You can buy a solid new bike for $7k - what a time to be alive) fuel efficiency, etc... but just remember that the more people riding is better for all of us (and not learning to ride on 636's... to increase their odds of survival), so I say bring on the P-twins!!!