Yes a little bit of both. People who want it now will refresh and if someone needed it for 2 weeks (or average time frame of rotation) then when it does appear they will buy it. Flip side of that if you know it's limited and you need one at the end of the limited time frame you are more likely to buy crystals to get it rather then wait and build up crystals over the following weeks.
The frustration is a proven element of the freemium model. I agree that you would think they would make more money if they "catered" to 2 tiers, the current one and a lower lvl one for people that would spend, but not in amounts that make it worth it in this model.
Informed spending is not in this model so they don't do it. I love to buy packs that have a price and an exact payout, I don't gamble with real money.