They do that now, it's called pre-ordering a game with exclusive DLC. Then a few months later they release all the exclusive DLC for download. Look at FFXIII-2, all the pre-order bonuses are now just available for downloads for a price. I pre-ordered the game, 2 copies actually, to get the pre-order bonuses I wanted than they just added them later. Actually it didn't bother me at all because it was my decision to pre-order 2 copies and I think people who:
[A] Couldn't afford it at the time.
or [B] Had some other reason not be able to play.
It shouldn't matter. These games are to be enjoyed to their fullest why punish people who play to collect because for the above reasons. They are bringing back other items that used to be only gotten one way.
Heck when I started playing I ran into a person with a Moogle Cap that helped me out, when I asked "Where did you get that?" They replied, "It doesn't matter because you'll never be able to get one." I was thrilled when they released the Key Chains that had it and I bought one.
Besides the money we spend helps the games we love.

If people are worried about their Tidal Talisman not being 'exclusive' anymore. Look at the Nomad Cap vs Moogle Cap. Can also make a new Tidal Talisman call it some else, change the color a little bit or the look a little, and give it same effect. Would still be just as nice to have in my opinion.