Our bridge is highly secure, and that is what we where aiming to do with it. It is expensive because security requires a lot of processing.
We expect our bridge to be the "wholesale" bridge used by other bridges as a secure channel to transfer large amounts. For most user L1<->L2 transactions it is sufficient to use one of the user facing "retail" bridges.
We want to improve how it works so that it is cheaper to claim on L1, but it will still be months before that change makes it in.