On the subject of value, that depends on individual perspective. Is knowledge of gravity, photosynthesis, and plate tectonics necessary for happy an comfortable surivival? Of course not. Value depends on how much you want to analyze the world around you. Some people don't like this kind of in-depth analysis, because frankly, it can get depressing and existential at times, and that's understandable. I think the value of evolutionary knowledge should be left up to each person to decide on their own.

On the subject of macroevolution vs. microevolution, yes, the two are intertwined to that extent. Because the concept of "species" is a human contruct, just as much as time. To assume that evolution simply stops under the species level assumes that nature works on human-defined terms, which is obviously not the case.

Plus, speciation has been proven. That shouldn't be in question.

I suppose common ancestory has more questions that arise, but some common ancestories are rather well-supported by fossil, observational, and genetic evidence.

I'm actually curious if scientists have ever thought about a "single origin" theory but slightly different, with multiple "origin" lifeforms. But then again, I'm less familiar with the concept of abiogenesis so I don't know how plausible multiple occurances of it are within the accepted timeframe.

Plus, the evolutionary tree as it is seems pretty sensible to me...