What nonsense, where is there any remote ambiguity? Where is it even slightly unreadable?

Reads pretty clearly left-to-right to me:

map[state]map[int]state -> a map of state keys pointing to maps of int keys pointing to states

    "map of int to string"
     map   [int]   string
    
    "map of state to map of int to state"
     map   [state]   map   [int]   state

In Rich Hickey terminology, it seems people reject that it is simple (non-interwoven) because it does not strike them as easy (familiar / close to hand).

( ...Any excuse to link to this excellent presentation: http://www.infoq.com/presentations/Simple-Made-Easy )