It's a given that plurality is useful. Operating on functional sub-units of universe is our "daily bread". Searching for unifying factor among those types is a harmful illusion. What is the unifying factor of a computer? Mother board? CPU? RAM? Electricity? You have to go really low-level to find physical unifying factor (i.e. chemistry, quantum mechanics, and below).

As for naturalism versus mystical idealism -- the more I look into it the more it seems to me that they are one and the same, but also sort of incomplete. Imagine a circular string. Take an arbitrary point on that string and suppose that it is completely still (idealism). Now take another point that is directly opposite to it and suppose that it is vibrating at maximal amplitude (naturalism). The rest of the string is then some form of transition between these two extremes. So, the question is not the amplitude of vibration, but what actually is that string.