Well, it's a very unexpected change no question there. It's not necessarily for the worse however. It does make the Paladins mount more readily availible, and therefore more useful, which I think is a good thing. The Paladin's Mount is supposed to be part of the Strength of the class afterall, and the fact is that it wasn't very often practical for the Pally to drag a huge, honking horse everwhere he went " just in case"
I think that it is very important to see what the new flavor description of the New Mount is as well, because it does signifigantly alter how this ability is perceived. In the Older Editions, The Paladin would have to track down that one special horse with who he made a connection with, While staring into it's deep, sparkling blue eyes....
(Cut to Beautiful empty beach with cheesy music playing in the background. The Paladin and his Horse race towards each other for about 5 minutes, staring at each-other longingly before embracing and spinning in slow, contented, circles)
Paladin: Noble steed, bond with me, and together we will destroy evil.
Horse: Neigh! (stomps twice and flips it's mane)
Paladin: Whoa there, don't get so excited! I didn't say I needed you quite yet! With all my whacky adventures, who knows when I'll need a good horse? Tell you what I'll do....I'll get you set up at a nice stable, and if I ever need you, and it's not too inconvenient to come get you, I'll come for you.
Horse: Neigh! (kicks Paladin in the face)
I would assume that with the new rules, it doesn't quite work that way anymore. I would see the mount as a helper sent as a gift from the Paladins Diety, Sort of a Guardian Angel with Hoofs that he can call upon when he needs help