Well, I don't know why such a location for your games would cause any technical issues such as a game crash or corruption however in rare cases developers name the folder that extracts to your chosen destination something odd, i.e not their name or the name of the game, making it incredibly difficult to locate in Program Files if you have a lot of programs from various publishers installed.
However, the average computer user has less games than they do 'programs' (for lack of a better word) so locating a game in a specifically designated 'game' folder would be easier done.
That's the only reason I can think off from the top of my head, I could be very wrong, infact knowing myself as I do, I probably am.