Mojang is particularly aggravating about this. They spent like a year completely reworking The End and adding hang-gliders or whatever, and meanwhile furnace carts have been broken for like three years, and the fix is apparently like a dozen lines of code or something. In fact the entire mine cart and track system should be overhauled if they're really serious about improving the game - but instead they just keep adding more stupid shit nobody asked for.

Not to mention a lot of the good mods are still on like 1.6 or something because obviously no one is going to diligently update their mod over the course of ten years or however long Mojang wants to keep this up.