They are games with RACING in them, but not RACING games per se...theres a difference. Kaz set out to make a driving simulator (whether thats a slogan or something he achieved isnt the argument here), not a racing simulator. Turn 10 set out to make their own GT series in Forza following same lines as Kaz.
Yes theres race tracks and a basic 'game' involving win make money buy car win more etc etc but that isnt the whole of the game. Its not critisizing the games just separating them from RacePro or F1 2011 etc etc...
For example GT5 wouldnt be called a rally game, yet theres rally in it, so just cause theres racing in forza, doesnt mean it is classed as a racing game.
+1. At various times both Poly and Turn 10 have been forthright about the fact that a racing game was not their focus nor intent; rather, the games were made as a celebration of the cars themselves, the experience, aesthetics, handling, etc. 'Racing' may be one of many things one can do in the games to that end, but it's merely one of many contexts, not emphasis.