I actually find these arguments plausible, but the trouble is that they, in my view, prove too much.

Well said.

Therefore, in at least some cases, I'm sure that people reject cryonics not because they're too biased to assess the arguments in favor of it, but because they honestly feel no identification with the future entities that it aims to produce -- and I don't see how this different subjective preference can be considered "irrational" in any way.

I think this is true. Cryonics being the "correct choice" doesn't just depend on correct calculations and estimates (probability of a singularity, probability of revival, etc) and a high enough sanity waterline (not dismissing opportunities out of hand because they seem strange). Whether cryonics is the correct choice also depends upon your preferences. This fact seems to be largely missing from the discussion about cryonics. Perhaps because advocates can't imagine people not valuing life extension in this way.

In particular, I personally can't bring myself to feel any identification whatsoever with some computer program that runs a simulation of my brain, no matter how accurate, and no matter how closely isomorphic its data structures might be to the state of my brain at any point in time.

I wouldn't pay 5 cents for a duplicate of me to exist. (Not for the sole sake of her existence, that is. If this duplicate could interact with me, or interact with my family immediately after my death, that would be a different story as I could delegate personal responsibilities to her.)