You really should try to explain why you think a change is needed (all changes not only this one), your reasoning for it?
Show us that you have an idea about what impact it will have and what your intended goal is?
Otherwise it only looks like a suggestion from a newbie that can't see the whole picture.
You do have a reasoning behind this idea, right?
In what way do you think this will "increase the importance of thievery"?
Importance as in high TPA will be absolutely needed to play the game without having to do blind attacks now and then (this is after all a strategy game not the roulette in a casino)
And your future plan for randomization makes all of this even worse.
"two categories - Espionage and Sabotage"
What would stealing gc be?
Espionage? "I was just looking to see if he had a lot"
Sabotage? "no I don't need any gc, I just want him to be poor"
Or will you remove all possibility to steal?