Well as a modifier to how much food is needed, sure.
Then again the whole 'realism' is imo not an argument - seeing how small the damage from being trampled is in this game, or how troops are counted and such.
If you don't like realism (weird as this game if you haven't noticed is trying to depict reality) then consider that it's just a square unfair advantage to have xx amount of horses in your party without there being *any* downsides to it. So it's from a realism and from a gameplay perspective problematic imo. On the other hand I love that I have the option of customizing the size of my inventory and gamespeed with this mechanic. I am not asking for a huge punishment though. Don't get me wrong.