Since Hasbro doesn't tell us anything, I came up with some theories on why they stopped making them.
1. Trained monkeys typing them up are on strike.
2. Management forgot why they added them in the first place.
3. Tired of trying to fix that damn typeset pRoBleM.
4. Couldn't find 4 friends for FX-7.
5. Know they can still charge $7 with or without an extra.
6. Stopped caring years ago.
7. Cheaper to use bad screen capture software for cards.
8. Tired of looking stupid over grammatical errors like 'imperal'
9. Phasing everything out. Next wave will come in a ziploc bag, then the next wave will come unpainted, then finally the last wave will have to be built from scratch.