1. the anchored putter takes the the swing itself out of play.
2. 2-handed bowling is a lot harder to master than bowling with 1. Once form is downpacked accuracy becomes the next and biggest issue to deal with.
3. The added revs can be an advantage but moreso a curse as the transitions are bigger and faster.
4. The equipment becomes limited and the layouts become more important as not to overflare.
5. Aside from that as a 2 hander, you are not taking the swing out of play, merely adding more torque.
6. Adding more torque means less accuracy because you are applying more muscle.
7. As I have witnessed Belmonte and Osku on there journey through the PBA, they has learned to relax their swings, slow down the footwork, and post shots.
8. This, however, has no effect on the actual swing path, there's no device to help any bowler deliver the ball through the swing path better or take the swing out of play, outside of practice and coaching.
9. My guess is that the USGA doesnt want to make the same mistake as bowling, in which equipment rules over skill.
I broke it down to 9 points which I feel covers your premise and I can compare most accurately:
1. The pendulum shoulder motion is still very similar.
2. Anchored putting is just as hard to master as traditional putting, otherwise, everyone would just switch over and there would be no argument. Not only that, but 1 handed bowling is just as hard to "master" and I would argue that on a house shot, 1 handed bowling is tougher because everything doesn't go right and funnel into the pocket. But that's beside the point.
3. Added stability can be a benefit but just as much a curse because of increased rigidity in the "hinge" causing your putter face to get stuck open.
4. The equipment needs to be more precise in length and use because too long or short of a putter or too much or little of a bend in the waist will cause the putter to be off line/get stuck open/closed.
5.
http://www.youtube.com/watch?v=vOij1prDhmI I see no swing there. Pretty much out of play. Not to mention speed is generated with the core in a 2 handed game, whereas backswing height generates most of the velocity in a 1 handed game.
6. Adding rigidity means less accuracy because you're more likely to get stuck or out of position.
7. As I have watched Els and Mickelson learn to use the long putter, I have seen them develop their putting games.
8. Players making the switch to a different putter employ coaches specifically for the switch and spend countless hours practicing. The different putter is not a quick fix. Much like switching to 2 handed bowling. It's not a quick fix. It's just something that in the long run provides an advantage in the power game.
9. If the USGA doesn't want equipment taking over, why do they allow the super golf balls, 460 cc driver heads, and steel shafts? If that was their aim, they need to take it back to persimmon woods and hickory shafts. A belly putter is no different than changing the span of your ball. It's not a different technology. It's a choice on whether you like your span stretched or relaxed.