Oh, yeah.  Warhorses are crazy expensive and I never really gave it much thought to gaming until I read the rules for Pendragon 5th edition.  And it's not like I'm riding my warhorse everywhere.  I've got my warhorse, my riding horse, maybe a second riding horse, a packhorse, and maybe my squire has a horse too.  But in some fantasy games, D&D I'm looking at you, treasure gained typically makes the expense of ownership of a warhorse trivial at best.
Oddly enough, I remember playing the Cavalier class in AD&D 1st edition and hardly ever fighting from horseback.  In my Deadlands games, set in the American west during the 1870s, hardly anyone ever rides a horse let alone fights off one.  And it's because a character must use the lower of their Fighting or Riding skill.  So to be good at fighting from horseback you've got to spend those precious skill points.