I’ve been always asking myself this question on why we can’t make little minecart train with chain item. Even MC story mode and MC dungeons had them but the base game doesn’t? We need a new update to make these more useful… to give a full reason to use the carts a Carts & Rails update is what we need.
I don’t think improvements to minecarts or the rail system should be approached as a method of travel. It’s probably important to consider, but elytra is just always going to be faster and more convenient. I think the minecart system should really be looked at as a way to move items. Especially with the addition of the crafter I think things like interconnected farms/factories/bases with automated ways to move items between them are going to be a lot more desirable. I can imagine freight train like systems if linked carts and long distance travel could be figured out.