With the advent of Gen 4 models, I do not understand why Glock would continue to manufacture Gen 3's. Yeah I hear that Gen 4's are plagued with problems (haven't had any issues with mine) but won't Glock get those ironed out and just mfg the Gen 4? Also I don't know why they still make the G20/21 and G29/30' with the advent of the "SF" models. I mean, with that logic, they might as well continue making Gen 1 and Gen 2 guns . Thoughts?