I think people under-estimate the importance financially and in terms of morale of a launch window, particularly to small independent developers. Getting written up by tech blogs or featured by Apple as part of the launch of an iOS version is make-or-break for many apps people make as passion projects, projects that don't start out generating enough income to be full-time jobs. The momentum from a launch day feature somewhere has been the push many needed to start building those passion projects for a living — or to putting serious time and emotional energy into making them happen. A lot of community favorite apps started this way — Drafts, Day One, Apollo, Instapaper, etc. So it's very personal to a lot of us in that community of smaller developers trying to grow our work.
When you have less than 24 hours after receiving a version of the software required to submit your app that has _new breaking changes_ that weren't on previous versions of iOS 14, and which will require significant effort on your part to fix, you're suddenly in a race against the clock. A lot of us pulled all-nighters, and there's still no guarantee we'll be able to launch today, because App Review can take quite a bit of time, even when they're rushing through the process as fast as they can.
We had to come to terms very quickly with the fact that Apple seems to have excluded us from the launch window almost entirely this time. Meanwhile, larger companies or organizations that have business models less dependent on interests from passionate iOS users will not really see as much impact — although quite a few small things in iOS 14 did break some of those apps, and they're probably rushing to get critical updates out as well.