In Vanilla Skyrim, whenever you fast travel, whether it be via the "Map-Warp" system, the "Carriage" system or even a mod that adds a "Mark and Recall Spells" system, your horse appears/loads in the destination cell standing right next to you. Even using http://skyrim.nexusmods.com/mods/17835/?tab=3&navtag=%2Fajax%2Fmodimages%2F%3Fuser%3D0%26id%3D17835 (by flatline42), which has a magic ring with a similar effect to Mark and Recall, your horse appears.

Now with the "Map-Warp" fast travel (which I personally never use), I could see why the developers scripted your horse to appear with you at the destination location.... sorta offers an explanation as to how you got to wherever it is you're fast traveling to (ie you presumably rode your horse there). But what about the "Carriage" mode? I don't ever remember seeing the driver load my horse onto (or tie-up behind) the carriage for crying-out-loud! Fast Travel via magical means such as "Mark and Recall" with your horse warping with you is even more ludacris. These two latter modes of fast travel do not involve your horse in any way, and having him/her show-up at the destination location is completely immersion-breaking.

So the mod idea I'm putting out there for consideration would very simply (hopefully simple?) put an end to "Horse Warping". If there's already a mod that serves this function (I've scoured and not found it if it does exist), linking me to it would be most appreciated.

Thank you very much for the consideration