Spelling bees are especially relevant for the English language, because its spelling is so highly non-phonetic. (I remember one grade-school teacher illustrating this by writing "PHOTI" on the chalkboard and informing the class that, given the wacky behavior of English pronunciation, it could even spell "fish" -- his (?) explanation was something like

"PH" as in "phoneme"
"O" as in "women," and
"TI" as in "pronunciation."

As a 2x former local spelling-bee champ, and 1x county spelling-bee champ, I must say I have mixed feelings about them. Like most talents, a photographic memory for spellings is something that is more luck than work, and so I personally felt strange at getting credit for something I had as much to do with as having brown hair. Also, success in a spelling bee, in such an anti-geek environment as rural Ohio was in my youth, was a mixed blessing. I really did feel a bit like a freak, though proud at the same time.
Note that ability to spell need not correlate with strong abilities in other seemingly related areas, nor does it imply strong "normal" intelligence. I was, for example, an ADD child, and in the practice round of the first spelling bee in which I participated (where I went on to beat the county round), I misspelled the word "nail." (As "nial").