The worst things you see in any game through skilling up are macros or repetitive movements that level skills. This destroys the whole idea of skilling up altogether, but can easily be fixed. Most games have soft caps on anything that levels, and any game could do something similar but allow for a system that prevents abuse at all. Hence we have degrading of skills on the basis that they were skilled too much. Example as follows:
Jumping is essentially a skill, in a sense, but it is tied very heavily to strength, stamina, endurance and agility. So to skill up jumping, you are essentially working to be able to jump higher and farther with less stamina loss. Typically, though, you could have a player macro jumping, go next to a wall, and come back hours later to have maxed jumping. Reality can be applied though, and this can be remedied. In the real world, if you were to jump in one spot for hours, you wouldn’t get very far. Further, you couldn't max in a day either.
So to compensate in-game, we add two scripts. One ties jumping skill-ups to distance traveled, combined with factors of speed used throughout, and how tired you were. The second script would enact so that over time, if you jumped too much, you would start losing skill, and your stats would temporarily suffer. In the end with this situation, you would have gained nothing at all. This should be a generous amount, generally, like 6 hours of mostly jumping, a number that would increase at least, as the skill level and stamina levels approached superior statuses. This idea could easily be applied in different ways to other skills, such as losing skill or stats with other physical skills, or simply putting a soft cap on intelligence-related skills.
Of course, this merely puts a cap on a bursting bottle, and doesn't truly remedy the issue. To do that, games need to have skills be interesting to level. To some extent, battling skills are inevitably tied to the combat system, so if your combat system is weak, so shall the skill leveling be tiresome. Crafting though, is another issue, for in real life, learning a craft is not very exciting either. So in essence, the key here is to keep it somewhat dynamic to maintain interest, as well as make a true crafting system that really rewards the MMO world as a whole.
Dynamic is not always easy though, as evidenced by the failure to really do so by any MMO out there. I would say it is still fairly simple though: let us take being a lumberjack, for example. Currently in any game you walk up to a pile of wood or a tree, and hit your gather key. This gets fairly boring fast.
Solution? Enable a combo mini-game, where timing certain clicks could give you bonus "swings" and thus remove time from harvesting. Also, making all trees harvestable would add a dynamic of placement with your harvesting, lest you depopulate the area too quickly. Crafting also commonly uses too much material, and with materials being able to be reused and less used overall, the system can stabilize a bit more.
This article will tie in to a future article that will be tied to how a world economy should work and what ideas should be done to prevent it from becoming boring or collapsing.