Are you really asking why you need to understand how basic electronics work?
In order to do just about any experimental work it is essential to know exactly what your intruments are telling you. And just about every lab out there uses some kind of electronics. I don't think you need to be an electrical engineer to be a good experimentalist, but I think you would be hard-pressed to find anyone working in a lab who would say they don't need to understand the basics of electronics.
In my job (medical physics) for example I need to understand how an ion chamber collects charge and an electrometer then integrates the resulting current so I can accurately determine radiation dosages. I need to understand pulse forming networks, leakage currents, and high and low pass filters. All of this requires a basic foundation in electronics.
Another way to look at it migh be that in a general physics course, you study precisely how basic tools work: levers, pulleys, lenses, spings, pumps, etc. and basic electronics is a natural extention of this.