Is it because the casino wants to create some rarity, I doubt it. I do not believe the casinos really care.

Actually, Warwick Stone from the HR posted at one point that he was trying to find the right amount of chips to release to keep us happy and maintain the secondary market value. Mark's recent post confirms that the Four Queens also has an awareness of the secondary market when setting release figures.

Why should a casino care about secondary market value?

two reasons

1) Maintaining high resale values of chips helps promote future chip sales.

2) In the past I have heard suggestion that not all the chips got released . . . That is employees intercepted them (and no I'm not talking about the Pai Gow chips). If you and your employees are grabbing chips to sell on Ebay its an added bonus for a $25 chip to sell for $200.