1. I have an idea for effecting maintenance costs:
Implement a small radiation in all systems, which will slow but constantly damage your ship and equipment.
Must be balanced well to avoid noob wipes, when they start with a Starflier.
2. Make the high profit runs less profitable and the low profit runs mor profitable. This will make players to follow their RP a bit more i guess.
I always start to become depressive, when making my Poisened Trash or Scrap run to Dortmund station, but i'm an ALG Trader, so i will not make high profit runs very often.