What is with Monstrous Mount Mastery?

I'm taking this line of feats for story reasons in one game, I'm not questioning using a feat to unlock more animal companion options, I'm questioning Monstrous Mount Mastery's necessity.

Unless I missed something, which is quite possible I admit, The base companions haven't required extra feats in order to use them as mounts or even flying mounts, so why do these companions you've already spent a feat to unlock seem to require it?

In my opinion the Mastery feat isn't worth it. But (also my opinion) the feat is only worth it for the worg mount (and its mastery ability isn't worth a feat). The hippogriff/gryphon are the only two that require the feat "to be a mount".

The only real difference between these and other companions is that these are magical beasts.. Really just talk to your GM about it, it's pointless to require a feat to ride something.

with out mastery
Normal: A monstrous mount is unable to use its Mastery abilities regardless of its advancement.

you won't be able to use

Mastery (7th Level)

Once per day as a standard action, the worg can make a fearful howl. This functions as the fear cone (30 ft.) version of the fear universal monster rule.

you only get on improvement normally at forth. the animal normally jumps up in size. i think the 7th lvl mastery is like the fourth lvl mastery. you still get all the normal stuff as you level for your animal companion (monstrous) just not the ability to scare people once a day (encase of the worg). it is a new power level you must invest time in training to achieve. with a monstrous flying companion sure it will be able to fly with you on it's back. but not as well or as fast if you have not spent time strengthening its wings to carry you and all your heavy stuff on it while in the air. the feat means that the ability to do it has been mastered and that you can fly faster with out you being thrown off (or something bad flying related)

I'm taking this line of feats for story reasons in one game, I'm not questioning using a feat to unlock more animal companion options, I'm questioning Monstrous Mount Mastery's necessity.

Unless I missed something, which is quite possible I admit, The base companions haven't required extra feats in order to use them as mounts or even flying mounts, so why do these companions you've already spent a feat to unlock seem to require it?

Its just an example of trying not to be leadership by adding more feats to the chain. Baking mastery into monstrous mount will make the feat more powerful, but its not even going to approach leadership even so and it wont break the game.