NavList:

This issue hasn't come up in a decade. Some of you may enjoy the comments section in this article on the Sky & Telescope website back in January 2012, in particular the comments from Rob Seamans and from me. 

And here's a brief --and lightweight-- paper I wrote on the topic back then.

John Clements, you wrote:
"As far as Celestial Navigation is concerned, it just sounds like one more row in the sight table: UT1 offset seconds ? Print it on every page of the nautical almanac, it won't take much space."

In short, I agree. There should be no problem for celestial navigation.

Another important community, which Rob Seamans addressed in some of those comments linked above, is the world of astronomical observatories. The smaller than one second offset is currently deep in old code and would probably break on many systems if the offset exceeded one second. While a new system can clearly be developed for providing the offset to Earth orientation time from a modifiedUTC without leap seconds, it takes money to get that done. And by the way, I've become convinced that it's important to define this as a modification of UTC rather than a new time definition (which traditionally it would have been). UTC is listed as the standard of time by law in many countries and other legal entities. That status should be left alone, if at all possible.

Frank Reed