The reason that TF2 doesn't get frustrating so fast is because the maps aren't stuff. Battlefield 3 or mw3 all have stuff maps, which funnel all the players in or out of a single area, while TF2 maps funnel players toward the objectives. The reason it doesn't get old as fast is because one team doesn't gain a huge help from the terrain and so one side doesn't keep bitchslapping the enemy team until the clock runs out.