Well...you're kind of forgetting the Seleukids, they used Chariots and had one of the most technalogically advanced armies of their day. Chariots still weren't very useful...but still....I don't think most of those things make fantasy, well, fantasy. I think they make it silly.
Chariots came into being because horses were too small to carry riders. Once horses could be bred large enough, they went the way of the dodo and disappeared - except in backwaters where they were done in by technologically superior armies.
And your forgetting this is fantasy, many armies that use chariots aren't very rational or...alive. The orcs don't use horses for one, so you can't apply that rationale to them, to the orcs having a huge spikey wheeley thing, pulled by two or three of the most ferocious beasts in the Warhammer World is a big plus. It's also probably a lot more effective than a normal horse drawn chariot.
Also the Tomb Kings come are New Kingdom Egyptian, they've also been sleeping for thousands of years, they are kind of out of the loop a bit in military advancements. However they make up for it by having a chariot and crew that can be brought back from the dead and besides, seeing a chariot hurdling towards you is probably very frightening, seeing one pulled by the living dead is even worse!
And yet you play 2nd ed 40k?But mostly my intent is to let the numbers speak for themselves. My goal is to design a clean, clear system that focuses on core combat, not special rules.
I know that a lot of people are going to be turned off because I'm not going to blind them with numbers or burden them with dozens of army-specific special rules. Oh well.