There may have been cost and schedule pressures that explicitly or implicitly discouraged a highly-formal development process for MCAS. But it smells more like a situation where the engineers involved simply didn't appreciate the risk presented and thought of it more as a bug fix or minor tweak not requiring formal process, rather than appreciating the risk but intentionally cutting corners on the sw dev process to save money.
Not sure I agree, especially when it comes to cert of aviation software.
There is a threshold to where a new version is easily certified for use, (ie expedited review) but that is usually reserved for corrections or modifications to existing code. MCAS was an additional feature, so that would have caused a major level upgrade and the extended certification process.
Boeing was under the gun to get the MAX certified with no new process or requirements, and the expedited review.(ie the $1 million per ac hit with SW)
So I feel that is why they did not tell the FAA, nor the Airlines about MCAS, (it was just veiled under STS)..
That disclosure would have initiated a new version, with full testing, extended review, and of course, the potential for additional training requirements, which we now know was not done.
Face it, there needs to be a V 1.0 of the FMS software, and leave out all of the legacy bugs. A $miilion per ac to SW would have been worth it against the $15 Billion it will cost them.