I don't see a problem with having to re-criminalise gambling every few years -- do you?

Regarding murder, I don't have a problem with having to periodically re-criminalise that either, though I think that for cases like this where there's enough of a consensus, the ban could be either permanent or much longer-term (e.g., every 50 years). In fact, having overly frequent votes on such serious crimes might encourage people to try to overturn them as a prank.

I don't think I trust our government on this. Look how many times they threaten shut down for routine things like increasing the debt ceiling; I can just imagine representatives threatening to not renew the outlawing of murder unless something else is added to the bill.