Probably because no one is buying the GPE or DEV edition of the S4, so its not like it matters anyways. People buy an S4 for all the great software TW brings to it, things no other phone on the market has. They don't buy one to get a stripped down, boring version of Android.
Wait..what? What does this have to do with the HTC One? The versions mentioned in this article are fully skinned versions running Sense, just carrier agnostic and free of carrier bloatware. HTC promised to have KK on these models in 30 days from release and as with their promise to rollout 4.3 in a timely fashion, they appear have met expectations once again. Considering their past update history before the One, this is very good news. I'd bet HTC has carrier versions updated to KK before Samsung as well.
And I personally wouldn't look twice at a S4 running TW, specifically because it's running TW. Until Samsung can't get their s%&t together and significantly alter and improve it, you'll never catch me running another Samsung device using it.