Type 2 = Modified
Type 1 = unlimited
Well the main reason is because Wizards of the Coast made the sets up to Skyridge. With that in mind, if Nintendo starts out again with Type 2, it would be better economically for them, since they don't need to reprint anything. Of course, plain Type 1 has been quite quick these days and the decks tend to be single sided, whereas type 2 has MORE variations between them to begin with.