It's interesting that Anthropic maintains current prices for prior state of the art models when doing a new release. Why offer a model with worse performance for the same price? What incentives are they trying to create?
One obvious explanation is that pricing is strongly related to the price to them, and that their only incentive is for people to use an expensive model of they really need it.
I forget which one of the GPT models was better, faster, and cheaper than the previous model. The incentive there is obviously, "If you want to use the old model for whatever reason, fine, but we really want you to use the new one because costs us less to run."
I'm guessing it's mostly for legacy reasons. When 3.7 came out many people were not happy with it and went back to 3.5; I guess supporting older models for a while makes sense.
