The increased head weights were/are to counterbalance the longer shafts and heavier grips that were / are typically used on these type of putters. If you put a traditional head weight putter (old traditional weight of about 325 grams) on an arm lock length, belly length or longer length putter, you will have no head feel. The new “traditional” head weight, or at least the head weight we design our putters for standard length applications is around 350-370 grams, maybe a little higher. At these weights they can be used at multiple lengths and still allow for build that maintains head feel. Of course the length, the weight of the shaft, the weight of the grip all come into play on how the putter will ultimately feel for the player. Also, the heavier head weights do provide some benefit in preventing inconsistent, or dare I say “yippy” strokes. Depending on how heavy the head is, counterbalancing may be needed to get the feel and consistency a player desires.