Because it's unbalanced. Sure, anyone can WIN, but there are a number of scenarios within the system where victory is flatout impossible. Since NPCs have a fixed number of maybe 7 cards and players only get "stronger" by collecting more cards, in addition to the overall random nature of NPCs in the first place, the rules "Order", "Chaos", and "Random" make no difference to the NPC but can cripple the player, ESPECIALLY the last one.
In addition there are a few NPCs whose difficulty isn't in sync with the MGP they award, especially any of the aforementioned Random using NPCs who pay out less than 100 MGP yet have basically the same cards as Rowena.
The mentality is the same as raiding, actually: "If victory is impossible for X level of player with Y set-up, then it needs to be changed"
I'm positive most of the NPCs will be unchanged, but there WILL be some that are either given a larger pool of cards, or have stronger cards replaced with weaker ones in order to keep their difficulty in line with their actual payout.
For example, Landenel will probably have Bahamut replaced with a 4 or 3 star card to keep him in line difficulty-wise with other NPCs that yield 53 on victory. My reasoning? Sezul Tuloc has the same payout but has 2 4 star cards, while Landenel not only has a more difficult ruleset to manage, but has a 5 star and a 4 star card.
