I have no intention to continue the battle of perspectives in a free market with the freedom of choice between the various house rules, however there is one thing that concerns me:
20kg+ bags in the overhead bins are actually a safety risk, at least from what I've witnessed myself multiple times (and those were probably bags weighing 15kg or less, not 20kg+).

Not so much during turbulence (hitting severe enough turbulence to cause such issues is very rare, especially on the routes Aegean serves), but during loading and even more during unloading of the overhead bins after the aircraft has parked at the destination airport.

I've actually more than once had someone basically drop his bag on my hands, which I'd placed above my head in the last second before it'd get hit.
I've helped others on several occasions either stow their bags in the bins or grab them at the end and I'd consider myself to be more than simply up for that task, yet I've oftentimes struggled to get those things up there, or to get them back down slowly, safely and directly into the aisle instead of in a seat!

Having toddlers myself now, I get up after we've stopped moving and put myself either in or over the aisle seat to block such things from falling onto them.

It can also pose a safety hazard during an emergency evacuation. Surely you're supposed to forget about them and just exit the plane, but I think we all know, that at least some people won't adhere to that rule, so imagine someone trying to roll that thing down the aisle during an emergency evacuation...