The fact of something being simple does not force it to be idiotic. As a matter of fact the simplest things are often the most functional and reliable. (think of tillers vs.wheels or furlers vs. hanks)
It worries me a hell of a lot more people trusting in space-age gauges and dials they dont't know how to read or use...
The oil "light" serves itself from a pressostatic switch to close an electrical cirtcuit which is normally used to turning on some sort of warning sign, although some instalations also feature an automatic shutdown to shut down the engine before lack of oil kills it for good.
I think it would be much more complicated for the simple user to have to know how to read an engine oil pressure gauge (do you know, for instance, what pressure to expect from your engine at idle, cruise and top rpm?) and understand its behaviour than just having to keep an eye out for the on/off state of a red light and/or buzzer.
The "oil light" is a very simple system used widely and for ages amongst almost anything with an engine and, as with every simple things, it doesn't break a lot and when it does it's easy and cheap to replace.
My advice is (assuming you engine oil level is ok) for you to have the lube pressure checked with a portable gauge and if the fault proves itself to be of the pressure switch have it replaced and forget it for a couple more decades.
Regards from Portugal!