Re: Single-coil question...
Hi Teledude; Welcome to the forum.
The quick & dirty answer is - its just another flavor of sound available, at the cost of a switch. Sorta like, why have just cookies, when you can have cookies & 'creme?
When you split a humbucker, you can mimick the sound of a Strat-ish single-coil. Maybe a little more, maybe a little less, depending on which pup you split. When you split a "tapped" single-coil, its kinda of like being able to go from "normal" SC sound, to super-charged sound. (Assuming, in that case, you switch the extra windings "in", rather than "out".)
Or, you may use the split function to better "match" one pup with another. For example, I'm about to put a tapped
Quarter Pound into a guitar. I may mate it up with a less powerful pup in the other position. So, I can use it on "full" by itself, but maybe, split it, when combined with the other.
Its all about options.
Artie