Been seeing this echoed across the official forums, MMOC, and Wowhead. Let me put some perspective to this one.
To start, I absolutely am okay with Blizzard choosing to delay Shadowlands, it was evident it was lacking some polish. Less straightforward is the reason for choosing October 1st, which some could argue shows they are still more focused on the Shareholder's than players. However, I am not here to give my opinion on either topic.
I am posting because I have seen a variation of the thread title posted throughout the internet in response to people rather upset they cannot get days they scheduled off back. My career changed drastically a year ago into a field I never thought I would be in. This field schedules days off a full year in advanced. You bid based off seniority amongst your coworkers. You can also take individual days in the middle of a year if you have the PTO saved for them and the day has not been bid on.
For Shadowlands I originally was quite lucky. The day after launch was a day off. However, I quickly went to bid on the following 3 days just to secure some extra time. I got one. I had to work hard to secure that day. I have the luxury of being in a position where my PTO is 14 hours granted per month that carries over per month.
People like me have no issue with this schedule change. I can go schedule more days off to relax and do what helps keep me less stressed when the new date is announced. Someone who is much less privileged would not be so lucky. For some people to even be granted a single day off, even in the Western World, is extremely rare. And to have to fight hard for that day and have them change it, in some peoples' opinions, at the last minute, really sours their mood.
TL;DR - Not everyone uses PTO for actual vacations. I use mine for errands and destressing. So instead of lambasting people for being upset they lost valuable time off work for the release, maybe, instead, you should focus looking at a bigger picture to their situation.
Thanks.