Right now even on hard difficulties game can feel to easy by abusing mob poor path finding, by that i mean jump up a few small ledges and the mobs seem incapable of jumping up, so you can sit back and fill them full of arrows and for most part they just stand there, maybe with some luck on there part wiggle just enough to bump up a ledge, but then you just change position.

Is they any mods that can fix or reduce this behavior, maybe something that allows them to climb smaller jumpable ledges?

Well, just don't climb...

There's a mod that gives them the ability to pathfind across rivers and streams so they dont just stand at the bank. They will actually dive in after you, and with the new underwater combat coming out soon there will be fewer places to hide.