Although constant raise of staff salary seems to be useless, it's needed as part of BB's economic system. Main goal of this mechanism is to force managers to change trainers - without it, some managers would be able to take all of the best staff members from the market. Other managers would be unable to get salary-efficient world-class trainers/doctors, or at least their price would become even more ridicoulous than now.
What about putting new staff members on market. I've heard that a log of them have graduated in academies recently and are waiting for their first paycheck. There are rumors that even they are willing to work for sandwiches. :-D
But what I would really like to propose is that those with lower level get a pop-up in skill once they have worked some time.