For the pure sciences, ya, you should do grad school if you want the bucks. Not needed at all really with engineering. Maybe later on for some particular specializations, or if you want to move sideways into a related field or management type of thing.
Not saying its meaningless, but its not a get your foot in the door sort of thing like it is with physics or math for example.
What usually happens in undergrad with STEM is that half of everyone who attempts it either fails and drops out, or changes majors in short order. At least to my recollection, the way its structured is a demanding first couple of years to wash out those without the chops, and then a more relaxed and specialized second two years. (more like 5 or 6 years for most people, realistically)
If you can hack a BS, you can hack a masters. Most people that don't make it know right away that they aren't going to make it. I say this as someone who got started in life before the Fall. I'm sure its quite a bit rougher now.