Allow me to clarify two responses:

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I think if we all stipulate that some form of "display UTC" is the only representation that should be stored or forwarded,

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You expect high-volume logging tools and network servers to convert every timestamp to year-month-day-hour-minute-second-subsecond?

A server that just accepts, stores, and distributes timestamps would simply store them in wire format. No conversions would be required. Only clients need interpret those "display UTC" convertible timestamps.

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you're kidding yourself if you expect UNIX filesystems to start storing inode times in that format.

I certainly don't expect UNIX filesystems to start storing "display UTC" convertible timestamps anytime soon. But I think it will happen eventually. The only issue that has stopped Olson "right" mode from being more popular is its failure to clearly distinguish between its TAI-ticking time_t's and the POSIX time_t's calculated or received from elsewhere. My observations about internal and external representations are based upon that practical experience. Thanks.