The manufacturer company put in larger engines than the aircraft is designed for. And they did it to avoid all the homologation licences and design costs involved in bringing a new aircraft to market with the appropriate tolerances, and to compete with another company's aircraft in time (Loss of sales).
They introduced MCAS in the aircraft for to balance by software a hardware issue, a big design negligent issue which can lead to stalling. It is beyond to trim an aircraft, and because of this there is a big difference in the scale of the values that the algorithm manages from a trimming.
It is not my field, but I think it is not a simple factor, and that it should not be put this over the Pilots like if it were a normal aircraft that received a simple update. Every pilot flying that plane should have been warned that it was not a classic plane with a classic update.
If this type of behaviour by aircraft manufacturers becomes the norm, costs over safety, we as passengers will suffer it, as other passengers unfortunately suffered it, while they blame the Pilots. In addition that nowadays the China's aircraft manufacturing industry wants to enter global market. Some days ago I read they want permission (homologations approvals) for to enter in the European Union.
PS: They also cut costs retiring backup sensors, delegating responsibility for a vital system due the MCAS to the buyer as if it was an unimportant feature; disaster was the order of the day. And the spending cuts were not limited to that, as we have seen in recent days.