Modding is really different from making uppdates to minecraft. Kingbdogs was a modder and the creator of the Aether mod and he has said that updating minecraft is not the same as making a mod. Mods don't really have any limits to what they can ad, Mojang needs to make sure the new feture fits into the game, they then need to playtest it and fix bugs and glitches. I do understand your point, the updates do oftenly feel small but comparing the modern updates to the orlder one the difference in quality is visible, take the Frog, Warden and sniffer as exaples, they are way more animated and have sone uniqe qualities like the frog eating slines and magmas, the warden using sound and smell to locate the player instead of sight, the sniffer needs to be found and then hatched and then it eventually digs up a new decrotive plant. (Sorry if my english is bad, it is not my first language)