I just worked on a massive "optimised" cloud migration like you've never seen. We moved from multiple DCs to AWS and the costs are approximately 8x what the pre-migration costs are. We were realistically expecting 2x which gave us some regional agility and was expected but the unconstrained growth and misunderstanding of the cost model was terrible. It's designed to be so convoluted that you can't possibly estimate costs until you get the first bill at which point you are committed on a multi-month or year project. On top of that the assumption at the time of development is the cost is someone else's so the sprawl since the migration is dangerous which means we cannot leave ever now we've embraced the PaaS options.
The whole proposition relies on the idea of a sunk cost being accepted.
So yes, back to servers please. IaaS should be the maximal offering that is accepted by a business from a risk perspective unless the tool or technology is disposable in a 6 month window. There is space there for gains. PaaS hell no.
Edit: worth mentioning that AWS support is somewhere near dire. We've had issues with multiple services and despite being a VERY high roller with enterprise support we can't get anything fixed in any reasonable time. It's just someone else's crap you're using and they aren't any better at it than you are, just adding lead time to any issues. In some cases I've had to actually call out complete bad implementations that break function guarantees provided by open source projects (I can't logically warn people away from services as it's pretty obvious who I am if I do). One rule I've developed is that if it's not a core project: S3, EC2, EBS, ALB etc then it's probably a commercial liability in some way. There are no people working or with any knowledge on some major bits of AWS infra.