2) We're not talking about 40% here you know? The amount of crit you can get from regemming and maybe using different gear will get to some 5% ish at best. So let's make an example for 5% haste vs 5% crit:
The fight length is ~20 sec and we have 3.0 sec attackspeed and ~2.85 with 5% haste.
In this amount of time we do
~ 4 CS + 4 DS + 2 Judgements + 6 white swings + 14 seals => a total of 30 attacks, that can crit =>
1.5 crits (this could be any number between 0 and 20, with an average of 1.5). But you could also say, that in 1 of 2 cases 1/3 of those 5% crit are wasted.
for haste it looks more like this:
Let's say the fight length varies for about 2-3 seconds so it might be something between 18 and 21 seconds:
So when do we get an extra hit? Answer: If the fight length is between 7*2.85 and 7*3 or between 19.95 and 21 seconds.
So the "chance" to get 1 extra hit is ~ 35% (1.05sec/3sec), because the fight length varies (and don't come telling me , that you always have exactly 21.01 seconds to nuke the valkyrs)
So in 2 out of 3 cases, the extra haste is wasted, but you also have to keep in mind, that haste rating is cheaper than crit (~25 vs ~45) and that an extra swing easily outdamages an extra crit.