Why not have both?
We are on the verge of a significant milestone in human history: within a lifetime we'll be colonising other worlds. Earth time will be meaningless in those other places, each world will require its own time system dependent on the rotation of that world. We'll also need a "universal" (pun intended) time which remains constant so we can do sciency&financial stuff.
This debate on leap seconds gives us the perfect opportunity to switch to multiple systems, with the first two being Earth Time (based on Earth's rotation so that 12pm is always when the sun is overhead, and a new Universal Time (based on the most accurate atomic clocks available) (not the same as the current UTC, please note!).
We also have the opportunity to make the new Universal Time metric. Because metric is sensible.