Totally agree.
I like to try and keep water and some quick snacks handy (ie not in the pack) whenever possible. And items like a map, compass or anything else which requires quick or ready access. It is a real pain to have to take a pack off and on to get access to something simple.

In cold weather people often just want to plod on, and if its wet no one likes to open up their pack, so having ready access is ideal.

When its hot weather, I've noticed that everyone drinks more water if they can quickly swig from a bottle which they have ready access to, rather than have to access a pack. I often keep a bottle for ready access, and a more in reserve in the pack.