I don't think GTA is the best example for "alternate navigation" through "destructibility". Apart from a couple of fences and lampposts, what can you really destroy that gives you new navigation possibilities? There are games that took this way further (e.g. Red Faction)
Yeah GTA doesn't have much in terms of destructibility. Some of the battlefield games do this pretty well though, particularly Bad Company 2. It was very common in that game to use explosives to make different ways in and out of buildings.
