I think there is application for both -Cutting boards should ALWAYS be end-grain !
For example, a cheese serving board could be called a cutting board, as you generally need to still cut the cheese from the blocks it's served in, but the forces involved do not require it to be end grain at all.
My family is largely non meat eating, so, in reality, our own board is pretty much a bread board. Which would be fine with not being end grain also. And, besides, most people would cut meat on a HDPE (or whatever it's called) hygienic thing now, rather than scrape away at an end grain to clean it.
So, personally, I think end grain are mainly just for show now. Which I'm fine with. Ours looks nice and is heavy enough to not slide about all over the place.