You are just determined not to have a digital display, aren’t you? Then fine, don’t. Keep your idiot light and pay a mechanic $50 to tell you what it means.
No reason to get all uptight about things. I’m just pointing out that your “obvious solution” has drawbacks. All solutions do, the real world of consumer goods is about picking your poison. For something that spends 99.9% of its life turned off a bland simple light gets the job done. And I don’t pay a mechanic to tell me what it means, I learned my car’s konami code and can find out what the light is complaining about just sitting in the parking lot. Of course my light doesn’t turn on very often, I take care of things.