I wish to see more abilities follow the model of my favorite skill, Slayer, that will be about killing creatures assigned by Slayer masters. Slayer makes OSRS gold training your combat skills more enjoyable by taking you around Runescape, also because it makes you fight so many distinct creatures, you get item drops that fuel an assortment of non-combat abilities --gems for Crafting, seeds for Farming, metal bars for Smithing.
I would really like to see that kind of diversity come to abilities such as Herblore and Agility, and I want to see more skills interact with different skills, such as the way I trained Woodcutting when leveling Hunter. Efficiency is enjoyable, and Runescape is at its finest when you are not stuck doing one thing.
Thankfully, some of Old School Runescape's more recent updates introduced minigames that help liven up otherwise boring skills like Cooking and Firemaking. And while some skills continue to be dull to train, they are at least more worthwhile thanks to the addition of skill-gated regional diaries that provide you with a globetrotting to-do record --kill this buy RS gold, speak to this NPC, finish this quest, craft this item and so forth.
Completing diaries unlocks exceptionally useful utilities and shortcuts, so they inspire you to train abilities and complete quests. They also supply a small but precious dose of management: if you need a new goal, you can always work on your own diaries.