Well the problem at the moment is that Smuggling missions are now so rare, that they're not worth waiting for. They might as well not exist, and legal cargo missions are boring as hell. Sothis was only so profitable because it was so far away. I think that was the whole point, the further you are from the central systems, the further you had to travel and the more valuable the mission. It was actually functioning as intended, but because it was one of few places that remote, people assumed it must be a bug.
Personally, my take on it is this: There's nothing wrong with filling your cargo hold with missions, taking illicit goods to far off destinations and getting paid handsomely for it. It's call "business".
What do you think a smuggler is going to do with a ship? Fill it with goods to smuggle and make as much profit as possible. And I'm talking REAL smugglers. Look em up, they do people drugs and weapons rather often. The payout most likely being a function of available cargo space, value of cargo, distance, difficulty/risk and of course, supply and demand. Do you think they leave port with spare cargo space? Do you think they ship legitimate cargo as well to fill that space? No and No. Although I'll concede that legitimate cargo might be used to camouflage illicit goods...
My point being, if that's what smuggling looks like on earth in the real world, then why the hell should it be any different smuggling goods through space in a virtual world that is set in the real world's theoretical future?
What I'd personally like to see is about 3x the number of missions. Just in general. But when it comes to smuggling missions, they need to be more varied and more plentiful. Cargo delivery missions both legal and smuggling, should interlock, one cluster of systems providing missions which take you to another cluster and so on, each cluster of stars should in fact take you to several (3-4) separate clusters, giving you the choice to work your way around a long range trading web. Maybe taking missions which increase in distance towards a specific cluster and planning your route accordingly. But most importantly, you should be able to do this without having to spend forever cherry picking the most profitable missions, in fact, you should be forced to carefully plan your missions to meet your cargo limitations/jump range/risk/reward/etc. You should be able to dock, load up/top off your cargo, refuel/repair/rearm and leave, all without checking the bulletin board every 5 mins and mode switching for hours.
Sure, the rewards need to be a function of risk/tonnage/value of commodity/distance/Reputation/rank, but there's nothing wrong with letting players make credits, if anything, having an easier time building your bankroll, means you can actually enjoy the other parts of the game because rather than grinding your chosen profession to the exclusion of all else, you have the freedom to use your profession to fund your extra curricular activities. Just. Like. Real. Life!