I don't personally mind 300 hour games but the way AC and most other games present them is exhausting. I don't want my map full of shit to do. I want to get the core experience, which should be the main story and after that sprinkle of stuff to do here and there which is all optional and there if enjoyed the world enough to keep going.
Why Ubi and others haven't figured this out, I have no idea. It's the best of both worlds.