Only for private API calls (and version 1 requires it as well). The only major change between ver1 & ver2 is that version 2 includes the API path in the hash (to prevent substitution attack). Public API calls (like ticker, depth, or trades) don't require authenitcation at all.
At this point there is absolutely no reason not to use ver2 unless you just enjoy your application breaking in the future.
Actually, the hashing in V0 == V1 for private calls, they changed it in V2, so although I don't enjoy the idea of my bot breaking the in future, I do enjoy the idea of being able to forward test my bot as quick as possible to refine the algorithm, which means using V1 is a doddle compared to V2