I dont think the battles was that difficult, I think that the farming requirement is. Despite most people I do had Old Ben 6* very close to 7*, so no big prob, but I didn't even had Leia unlocked before the announcement that she would be needed and even with the pack there is no way to level her up to 7* unless I really go crazy money-wise with the crystal pack. And I do play for a hell amount of time and get #1 in my Arena and occasionally spend money in the game, so it's not like I didn't have any plan or play by chance, I just didn't had a single character that was no way essential so far.
The event was targeted for p2p, no questions on that, even if f2p happens to get CLS because they already had the require chars beforehand. If you don't have a single one of the chars they didn't gave you enough time to get them unless you spend money in packs and, to make things worse, to unlock Luke is all or nothing: you get him at 7* by having all chars in 7* and decent gear, or you get nothing at all since you can get CLS 6*, 5* or so on... it is a very shameless way to release a maybe game breaking toon.