The starting point for a Coase bargain is here, now. If you successfully get the laws changed before bargaining, that gives you a different starting point for bargaining.

If you do have the ability to reliably get laws changed at some expense, you should bring that up while bargaining; it will give you a stronger position. You should be able to get a deal that's better than actually spending whatever resource it would take to change the law.

That makes sense to me.

This is an interesting perspective. Can I ask what your background is that exposed you to this way of thinking?

Lots of reading game theory & economics, and saying "that doesn't make any sense," then reading it again until it made sense. The "rationalsphere" is where I read most of it; sites like lesswrong, overcomingbias, putanumonit, and thezvi.