the map node ensures that the output will not exceed the range given in the destination minimum and maximum.
but you are talking about ioboxes and the user interface. the minimum and maximum setting on the iobox restrict the behaviour when scrolling through the values, but they do not affect values which are manually entered.
this is on purpose, as the min max values are just a suggestion for the user, not hard constraints. all vvvv nodes are supposed to deal with out-of-range values. for example the midi nodes will deal with channels > 15 by using just the lower four bits of it. so it might not even necessary to really restrict the users input.
i have to admit that is currently not possible to do what you want with the iobox, as its either configured as an input or as an output (in principle someone could start using setpatch to come across this). but in fact the iobox (although advanced) still misses a lot of features, and hopefully there will be a day when we manage to rework the whole subtype concept, which will allow you to do what you´re describing.