Well, I guess maybe they didn't want things to get too out of hand and now if they want they can be back up soon with that fixed.
And that's exactly what is so wrong about the NSA and others not being good stewards of their own bloody malware. A lot of these criminals would not be able to get their act together at this level without being partially funded by the three letter agencies. Think of it as an advanced form of script kiddies, they can use the tools and wrap them but they could not come up with those tools of their own accord.
They were clever enough to execute this attack, collect over £160k according to the last estimate I've seen (likely way more now), and achieve that in one day. You seem to underestimate them including assumptions that this was simply missed. There are many potential scenarios where this is beneficial to the authors.