Personally I love the Hardcore setting as it makes players sneak around abit more and play more tactically, and although I see your point about the sniper rifles there's nothing worse than lining up a perfect sniper shot on non hardcore, shooting someone just to have them carrying on running as if nothing had happened!

A comparable unrealistic trait of non hardcore snipers is pretty much every other non hardcore gun take the RPD Heavy Machine Gun for instance, I try using this in non hardcore and have to use the 'Deep Impact' perk just to make it as powerful as for example the P-90 (which players fly around spraying everything with in non hardcore)and in close quarters I still lose 9/10 1 on 1's with it against supposedly much less powerful weapons.

As for knowing where the nades are it does kind of defeat the object of having them if peeps know which way to run to avoid them