Big damage characters aren't supposed to be string-reliant. What we have is a bunch of kasumi-adjusted rushdown players who can't figure out that Phase 4 isn't meant to be played the same way. And they can't adjust and so they bitch and whine.
Maybe she is viable against randoms who don't know what they're doing but she certainly isn't against someone who understands throwpunishing or interruptions.
Smarts and patient play wouldn't do you any good against a spacing character like Ayane or Jann Lee, who also throw punish. P4 is shut down in every way in this scenario. 3P+K P can be easily avoided. Big damage? Other characters are capable of doing big damage, too.
Thus far, its a lot of talk and not much content to back it up. If there won't be any content because "its online" then this entire viable/not-viable conversation is pointless.