Engineers dealing with hardware and manufacturing are held back by the fact that they require a lot of investment to get to market and have to often depend on a large number of people to get the product out of the door. This is where even non-technical MBAs & bean counters can have an upper hand over Sr.Engneer. So it would make sense for Techies in these areas to arm themselves with a MBA just to stay competitive. But for those in Design, Simulation, Software a MBA is not all that critical unless they want to manage a large Team or get into the start up mode..
For engineers transitioning into management, some only need the basics of business practices to succeed. Knowledge and good communication skills are much more important than a lot of business theory.
If an engineer wants to start a company, then they need to partner with someone with a good business background.
I would only consider an MBA if there were specific business opportunities that rewarded the effort. From what I have seen, an engineer with an MBA is not that valuable unless they the solid engineering background and the skills I discussed earlier.
Just my opinion.
I agree with the sentiment that if your employer is willing to pay for it, then it would be worthwhile. That's assuming your main career objective is to climb the management ladder. Otherwise I would skip it.