Right, but (a) that only defers the problem to the future (centuries), which will have ever faster increasing delta-T, and (b) in the short-term you'd have to change all the existing infrastructure for astronomy and satellites which rely on the broadcast (by NTP or whatever) clock signals to be UTC. There's too much that could break; therefore there's a preference for "never change a running system". Of course, there's disagreement on how well the current system "runs". But it's not as simple as saying "oh, let's just drop leap seconds and everything will be fine".