But SE's testing and QA has always sucked, they don't even test the stuff they directly change properly. See: 2h weapon update.
It's impossible to say without actually knowing what SE was thinking but I'd bet the 2H buff wasn't a mistake. Blizzard recently gave a talk at GDC that referred to their techniques for adjusting and introducing jobs in a beta program. Though this isn't beta the same principles apply, and the logic goes like this:
1. Whatever job or action needs to be adjusted almost certainly has a stigma attached to it (it's gimpy, useless, etc).
2. A measured buff that brings this job or action in line with where it's supposed to be will almost certainly be dismissed by the community because of simple psychology.
3. You can't possibly test all of the edge cases as well as your 500K+ community can.
So, rather than doing one perfectly targeted buff or a series of smaller buffs spread out over time, you do one massive buff that's
intentionally over-powered. This grabs the community's attention and causes tons of people to level that job or skill up that action and use the crap out of it. They'll quickly reveal exactly how over-powered it is, at which point you can slowly back the changes down to a more appropriate level.
Using this technique you get the community aware of the useful changes you've made to the job or action. When you back them down people will complain a little but they'll generally agree that the "nerf" was necessary, but they'll still see the usefulness of the buff. You end up at the exact same place you would have been with a series of smaller buffs except this way your players actually notice the changes.
This is almost exactly what they've done with scholar, too - rather than make a series of smaller changes they made one big fuck-all change and, if it turns out to be over-powered, they'll deal with that when it comes. But this way they've gotten the community's attention and that's what you really need.