I drove an '88 Mazda RX-7 with both, and they were quite valuable! The coolant sensor saved my ass more than once by alerting me to a small leak before I'd lost too much coolant (hose under the intake manifold failed, hose to the firewall failed, radiator cap gasket failed.
Nobody has low coolant or low oil sensors!
Something I've realized over the past few years poking with a large variety of cars:
