It is true that plate armor is not as heavy and restricting as people think, but it is definitely quite heavy (compared to other armors) and makes it much harder to do agile stuff. Yes, you can roll in them, but why would you wear it, if you focus on avoiding hits, not taking them.Real full plate armor is not that heavy or cumbersome. Normal people can do handstands and summersaults in it.
So geralt rolling in plate is no more unrealistic then him rolling with two swords on his back.(also lol at drawing a longsword from your back)
Anyway, even the early "heavier looking" armors were quite silly (although acceptable), but this one is just ridiculous. What next? Make Geralt fight in helmet? Wait.....