This is one of my favorite 4th edition rants, but I strongly agree that Beastmasters / Cavalrymen focus has changed a great deal during the various editions. Panda pretty much said that the 4th edition developers considered that the primary focus of the Beastmaster discipline to be the "Savage Warrior", and mastering beasts was only a popular option. But instead of ether renaming the discipline to "Savage Fighter" or splitting into two disciplines, we have a discipline named Beastmaster where only two of the first two tiers discipline talents are about Animals/Beasts at all, and all the other Animal Talents are Talent Options.
In the meantime, you are quite correct that the Cavalryman has all these Animal Bond/Animal Training/Etc. talents that make him perfect for being the master of a traveling claw fest. Maybe three of four mounts for different situations (indoors, rough terrain, etc) and a few other animal companions for fighting/scouting/theft/watch-standing, etc. And nowhere in the 4th edition books does it say he can't/shouldn't use his talents to become so.
The thing that has me so confused about the discipline is that if you go back to the older edition splat books, the fluff text waxes lyrical about the special bond between a Cavalryman and his one true mount. It is unthinkable for one to have a remount. Or to bond with any animal other than his one true mount. Now nowhere is that fluff repeated in anything 4th edition, but is it still something that anybody should give any consideration too? Has the discipline simply evolved too much since that was written that it ought to be ignored? Or is the fluff still canon? In which case why does the Cavalryman have Animal Bond as a discipline talent, when it is not supposed to be used until or unless his loyal pony dies? I mean he has all the Talents required to manage an entire menagerie, but the older edition fluff text says he should not do so. I am confused!