If I had to guess? They're probably wanting people to have to spend everything at the time of the Event
If they bundled Event Currency + Diamonds then the best deal ($200) would most likely be something like Diamonds + 29% value in the forum of Event Currency. You would be able to spend the 29% and save the rest of the Diamonds for something outside the Event
Now, I don't have a screenshot of what the $100 deal used to be to compare with, so I only have the $200 package to go off of because that I did take a screenshot of (but it's also from the Summer Event..... so hopefully the deals are consistent enough across Events to be good enough to use the old Summer $200 deal lumped with Event Currency to compare with)
If we were to apply that 29% to the $100 package then you'd get something like this:
14,000 + 29% = 18,060 Diamonds / 1,995 per package = 9 packages of tickets = 5,657 Tickets total (from the old deals)
We're not getting the assumed old value of 5,657 Tickets, we're getting the new value of 7,770 Tickets but it has to be spent during the Event. Can't save it for a future Event.
Personally I do prefer buying Diamonds + 29% worth of Event Currency bundled into it. I too am in no way interested in buying exclusively Event Currency on its own. Because I would like the option of saving something for a future Event and not having to spend every last bit of it on the current Event.
I wouldn't mind it if they had two offers side-by-side. The new method and the old deals. Then we could choose which one we prefer