As an adventurer let me put my 2 credits in on this discussion. Sneaking used to be the best part of the game for me. I would take hard missions just for the money. Was it fair? yes! Why? Because, it takes a long time to sneak through missions. I would spend on average 2-4 hours on most missions (I like being tourough and checking every room). Aside from the money and items from chests the reason I did it was because it was teeth grinding fear and excitement. You had to be very skilled to open a chest, turn sneak back on, loot item, turn sneak back on, close chest, and trun sneak back on again without a red mob seeing you. What really made it tense was that you knew if the mob spotted you, you were dead. You had to time everything just right and even when you did, you still got noticed and killed a couple times per mission.
Being an adventurer I am a soloist. It was a challenge just to survive and that's why I want to be able to sneak through missions again. IMHO it is not unballancing because you generally spend 3 times the amount of time a soldier or other class would take to finish a mission and you don't get any tokens. All it's really good for is the excitement and the money.
There will always be those who do something that was not intended with a skill but sneaking is a viable alternative play style and should be allowed. The benefits are few since you can't get tokens unless you kill the mobs so why not put it back like it was?
Even the money reward is crap these days on misisons..the average mission at lv 50 nets me about 10k when at lv 28 I was making 40k per mission on an even mission. Hell, I have trouble buying med kits, chargers, and nano first aid kits now.