Some have mentioned that some popular maps were not designed with grappling in mind. I would like to discuss the differences between designing a map for walking/running/jumping movement as opposed to having the addition of a grapple hook.

What details would a map have in order to be deemed 'grapple-ready"?

What details would make a map not-suitable for grappling? (perhaps mention a known map as an example)

The answer is pretty easy: Those maps, that have much opened space, like greatwall or facing worlds, are not suitable for grapple play, as you can draw a line easily from base to base, resulting a very fast way to move.

Controlfactor seems a very grapple friendly map: you still has the ability to move anywhere without the grapple, but using it will help you probably. Eg. when moving in and OUT from the nmy base. You can use the jumppads to get to the teleporter out the base, but you can use your grapple too.

The problem with Nexuiz's garpple is IMHO, that it's offhand. (Offhand means grapple is not another "weapon", you can use it whenever you want, you don't have to switch back-forth your grapple and your last used weapon). I like onhand grapple much much better, as you need to think about the risk of using the grapple: you can't shoot back, your only weapon is your speed - if you're doing well. But as divVerent said, it's currently impossible to have onhand grapples in Nexuiz, as we can't have more weapons.

However locking wepons in nofire with the current system when grappling (tm) would be easy.

We can't have more weapons? Why not? This can be fixed in code. Please do .
I was thinking that nexuiz should maybe also have a realistic weapons set along with it's regular weapons, and that in the server setting there should be the ability to swap out any weapon for any other weapon.