All my life spent working with machines, I am a retired commercial helicopter pilot, I have manitained the most important part is the engine.
If you look after nothing else, at least look after the engine.
I want to know at all times what the engine is doing.
If when in Cruise control I want to overtake another vehicle, I need to know when I get to, say, 3,000rpm, so I don'r exceed the 'red line'. I can only do that if I can see a Rev counter.
Incidentally, the 300h has the Rev counter available in Cruise control!