People already cry about losing things inside their base when offline. Now you want to have your horse graze while you're offline just so you can log in, see your horse gone, then come to the forum to get all upset that someone stole your horse. Gonna cry for stables and electric fences operated by batteries made from mixing metal frags, sulfer, and water?
While I agree a faster mode of transportation could/should be incorporated, I don't think riding animals/dinosaurs/each other will be the answer. I don't even think bikes would be that great with the current concept. Imagine coming up to a road way and see a pack of nakeds getting their Lance Armstrong on.
That logic is great - if the players will QQ about losing it, we definitely shouldn't add it.
Y'know.. like blowing into peoples houses and destroying hours of work wasn't a controversial addition or anything either.
If not animals or bicycles, what other form of transportation do you want?
Cars? No. That idea is even worse then bicycles.