We already get gear for doing old content via tombstones... It's fine as is. Making the drops from the old content relevant for current content would just make it easy for SE to say hey, this stuff is still good to go, we don't need to make more. In turn well let's be honest, the fights would get old even faster and everything would just be on farm status. At that point why raid?

If FFXIV is going into maintenance mode and they aren't developing it in earnest anymore, sure. Otherwise, no.