To actually address the "snack" issue:

No AA does not offer a snack basket like some other domestic airlines do.

"Snack" is actually a defined meal on AA (and much more substantial than a candy bar or a bag of chips) and no a short flight like DFW-MCI would not get a snack.

DFW-MCI is coded as a beverage service only (and that shows up if you look at the details when booking on AA.com). Yes you typically do receive the little package of snack mix in first class on those flights, but it wouldn't occur to me to write in if it was actually missing on one flight (see least substantial things to complain about thread referenced above). Most likely you got the response you did from AA since you said the snack was missing - and as I said above snack is a defined meal which your DFW-MCI flight definitely wouldn't get.