Let's talk about 2.1 freeze

[Allyrion]

It's 1 second longer, not .5 seconds. Unless you're including the GCD, but you might also want to consider the chance of interruption.

As for the placement part, I wasnt even thinking about that.

Yes, Blizzard II's cast is 2s but it's cooldown is 2.5s. Also, the gcd is 2.5s so you're never going go below that (well with spell speed, that affects everything universally).
So essentially the time differenc is 0.5s.
You are right about a larger inherent chance of interruption but also consider that you are in less danger of this because it is actually a ranged ability *and* a bind.
I think it's pretty safe for what it is.