It's a considerable buff. It's not like he'd be the first to have multiple stances:
Christie - JaK and Roll
Helena - Bokuho and BT
Ayane - BT, 11/33 and roll
Brad Wong - BT, Handstands, Laydowns, and Crane Stance
I only mention back turn for one of two reasons.
1. The character can literally fight your with their back to you the whole time.
2. The BT includes a forward dash that will progress you character close to the opponent without leaving BT
Usually both are the case. I've already voiced my opinions on why I thought his old wind dash should return though. The new wind dash is great but as a stand alone dash it doesn't seem like it should be his primary dash. The doa4 wind dash was always means to an entry. It had an elbow that gave good stun on NH, a mid kick mix-up that knocked down, and a low kick that would drop the opponent on their ass if they decided to just chill and block. In addition if you opponent decided not to whack buttons when you're coming in, Hayate could use his throw as a mix-up for pretty good damage. On top of that the teleport was there, raw.
The DOA5 Wind Dash seems like it works better as a cancel, while still being allowed raw just for the sake of the guard break, which is what covers the bases of both of the other options. The mids were both launchers, unsafe but launchers. You have the 50/50 on that but more importantly to mess with people who guard after being mixed up into a wind dash mix-up on guard, you've got the +7 guard break and the throw itself for some good advantage or damage.
So if you're following, the initial wind dash is like... a way to come in really fast and really long distance with the mix-up value covering its bases as opposed to the new wind dash which is for basically putting your opponent into the air for a juggle while having a way to cover both of its bases on those launchers with a great gb and throw.
Can't argue about too many options either since most of those other characters still outnumber Hayate on options from their stances combined.