If anthropics makes any sense, then cryonics in a Big World is still controlling what you should mostly expect to experience. The anthropic escape valves for a version of me who experiences death and remembers not being signed up for cryonics range from Boltzmann brains to lunatics to completely random ancestor simulations, and I think I value experiencing the mainline expected cryonics outcome more highly than I do experiencing these.

And even if anthropics doesn't make sense, then as a matter of decision theory I value actually being around in a substantial fraction of the futures of the current world-state.