Well, I guess maybe it just boils down to playing time. I have a hard time imagining that a user hasn't seen a player break a gang tackle for a TD. I cant imagine that a user hasn't seen a player get drug as they "fall out" of a broken tackle. On the default All Pro or All Madden settings, I cant see it taking more than 30-40 games to see either of those.
Pro Tack was sold to us as "Dynamic" and a "Technology" that would respect players weight, speed and momentum.
Its already been proven that Pro Tack renders the hit stick mute a majority of the times. Its also been proven that Pro Tack has a strong tendency to suck players into the gang tackle animation. Just on those two examples alone, I beg to differ from a user control standpoint.