Shocked? It makes perfect sense to me. All the animals they have in the book are fighters. If I recall correctly, aside from the boar, they are predators that take down live prey. They have claws, bites, and tusks, not just hooves.
It's also probable that they didn't want to have to deal with combining the mount rules and the beast companion rules.
I was shocked not to see the Horse amid the possible beast companions. We got a giant spider but no horse! I had hoped for Apes/ monkeys (and I know you were too!) and perhaps dolphins or sharks but no Horse!
And for gorillas you can use Bear stats.For monkeys you just use the Spider stats: Climb speed, good Dex score, it works out.
I was shocked not to see the Horse amid the possible beast companions. We got a giant spider but no horse! I had hoped for Apes/ monkeys (and I know you were too!) and perhaps dolphins or sharks but no Horse!