I would like an answer to this as well. Haven't played the game in quite some time, and was wondering on the profitability of the crew skills.
I recall back in the day, Slicing made a decent amount of money, but then was nerfed, and now I'm curious how it stands out compared to the crew skills in terms of monetization.
The problem most "haters" have is that they fail to view it from a long haul perspective. They do 10 lockbox missions find that they are losing money and believe it got nerfed too much. They do not take into account the nodes just lying around waiting to be collected as "free credits," nor do they take into account that no other crew skill costs nothing to level. Over the entire leveling process, slicing WILL generate credits gains. All other crew skills you have to spend credits to level and unless you sell everything you gather or make, those credits are gone.
Armortech and Synthweaving wont' be useless since they are needed end game augments (willpower, strength, defense..etc for synthweaving and aim , cunning..etc for armortech.)
Along these lines, do not ignore prototype (blue) quality augments for money making purposes. Prototype quality augments sell for an average of 10k each (all of them fluctuate between 5.5k to 15k on my server) and the materials are valued at less than half that. You will not make millions overnight, but if you are patient it will be a nice steady income.