I hate tzdata updates with a passion, politicians should just get a grip and stop messing around with timezones. I'm all for ideas that create new jobs but this isn't one of them.
I.e. gradually slow/accelerate time over the course of a day, rather than stepping it hard at once.
I'd say this approach would be vastly preferable for about 100% of the systems relying on pool.ntp.org.
The remaining 0%, e.g. scientific applications that absolutely need the leap second to appear at exactly the right moment, most likely don't use pool.ntp.org anyways.
And for those who do they could create a second pool with the old behavior. Maybe call it science.ntp.org.
When you look at how much people crap their pants over the leap second - a relatively common thing - I dread to think how unprepared people would be for something 3,600 times less common.