This is total speculation, but considering that it's nearly 2 months before the D2 PC release plus this is Bungie's first attempt at a complete PC build (not a port), I suspect there will be another Beta period before Oct 24. It will showcase things like improved (and less sensitive to legit apps) anti-cheat detection, adjusted and tuned aim-assist mechanics as well as more specific PC hardware and configuration guidelines.
I have no basis for this theory other than the brief period of this PC Beta and some of the overly broad mechanics and information that was provided. It makes me feel like this Beta was more about gathering data (most common hardware/legit apps being used), getting a general idea of how the community felt about some of the in game mechanics (aim assist/FOV/button layouts) and identifying the most common errors so that help articles can be prepared.
I'm probably totally off on this, but I really get the idea that Bungie put a lot of effort into this build. They'd rather take their lumps now and correct the issues before the release.
It would be a pleasant surprise though. You brought up a good point. On top of being a very short Beta, it was during the middle of the week. I'd guess they did this because they were still feeling out server loads. Obviously this Beta had more players than usual because console owners played just to scratch the D2 itch and almost everyone has a PC. Even with the extra players, doing a Beta in the middle of the week still isn't a real world stress test. I just have this feeling that they will want to see what peak hours looks like at the very least.