This might be a fairly complicated system to implement, but I think it might be worthwhile to implement a system by which it becomes easier to improve your skills if you have someone or something to learn from.
This could be achieved through a "teach" command, specifying the skill you want to teach - I.E. "teach Electro Tech to [name]" - which initiates a short session where you mentor your subject on your skill (taking some time, and perhaps some repeated "teach / learn" prompts to prevent idling). Success depends on the difference in skill between the teacher and the student, as well as the Intelligence levels of both participants (or maybe strength / agility for physical skills).
Success doesn't automatically grant advancement in the skill you trained in - as always, the only way to do so is to assign UE to the skill as appropriate. However, if you have successfully benefited from teaching, the cost to improve the skill could be lowered slightly up to a point.
This also opens the door to be "taught" by game objects that you could purchase - books, exercise equipment, training / practice materials, and the like. Using these materials for self-teaching would likely be more difficult or incur a lesser benefit, and more advanced materials might be required the higher up you get in a skill - after all, "basic programming" isn't going to be any use to a skilled programmer who knows everything in that book backwards and forwards.
This could create new markets in the game - for mentors, teachers, and tutors to offer their services - and might also pave the way for highly skilled individuals to write or create their own training materials for others to purchase (which might require a new "writing" skill in addition to relying on the skill they want to create a manual for).
This also gives incentive for new players to seek out experienced players and interact with them, in order to more quickly raise up their skills from the starting level.
Does this sound like it'd be a worthwhile addition to the game?