Uncovered dyneema used as lifelines won't last 5 or 10 years; nor did I expect it to. If used as standing
rigging, any area expect to see chafe should be protected; but that area/length is minimal compared to the total length of
rigging.
Also, the standard 12-strand braid of Dyneema is extremely easy to splice (even without tools) and one can carry the
line required for a complete
rigging change in a canvas sailor's bag. Apart from not having room for the same amount of wire rigging, one would also need tools and spares for swaging wire.
Despite my liking for Dyneema, I opted not to use it for standing rigging as I'm a cruiser and not a racer and any weight savings in the rigging would immediately go to additional storage belowdecks for "stuff".