Vanderleun recently put this up over at American Digest (which I may put in my sidebar), along with commentary.
I was not a Glen Campbell fan in 1968 - I was too cool for country and that fresh-faced look, y'see - but the songs he put out then have stuck with me better than most others.* Many of them were by Jimmy Webb, as this one is, and those have had legs.
Vanderleun's take highlighted for me how the arrangement supports the lyrics: the bass solo is exaggeratedly electric and machine-like; the violins are super-high on treble to capture the whine referred to in the first chorus. The tune itself goes into the high ranges at that point for the same reason.
*Okay, not "Where's The Playground, Susie," or "Dreams of the Everyday Housewife." Those really were execrable.