Some delegates to the ITU-R process have argued in the above fashion. Other delegates have come representing countries which want UTC to remain as a valid count of days in the calendar (for 86400 SI seconds is not the same as one rotation of the earth). For over 10 years these two viewpoints have been at stalemate with no progress toward any compromise that might alleviate the problems that POSIX systems face at each leap second.
I would argue for both fixed UTC based on atomic clocks, and 86400 seconds per day - at the expense of rotation of Earth not being in sync with UTC or calendar boundaries.
It will take 3000 years before leap seconds add up to an hour, but most countries adjust the clocks that much every year for DST. It will take 40000 years before the usual daytime hours turn into night, and by then I hope a single planet's rotation is a historical oddity.