I'm surprised the introductory 50% discount is good for 4 months. It seems like frontier models release new versions every 2-3 months, so raising prices in 4 months seems like a bad plan: you're effectively planning to charge users twice as much for a model that is no longer frontier.
The goal is to encourage users to move to the next generation. The fewer models they serve, the less excess capacity they need to provision.
Serving more models also adds a significant ops burden on the SREs and trust& safety teams.