Apple Watch 5 and iOS 10 side button

As someone who used to use the Application Dock set to 'Favorites' rather than 'Recent' I find this change really disappointing and irritating, since 'Favorites' is no longer an option. Generally speaking, the changes for how to invoke Control Center and the Dock themselves aren't really much of an improvement; it's just different. Before WatchOS 10, having side button bring up dock made sense and doing a 'swipe up' to get Control Center was easy as well. I failed to see any problems with this previous arrangement and the new changes seem hardly a big improvement. But the worst part of it was what I first mentioned; the fact that 'Favorites' can't be set for the application dock.

Yes, as mentioned Apple changed this behavior in watchOS 10. To see your recent apps dock, double press the Digital Crown.

Unfortunately, you cannot specify favorite apps any longer—instead, double pressing the crown shows all your recent and open apps.

There is no way to change the behavior of the side button—with a single press, it always opens Control Center

That is a new improved UI. Cannot be changed.

Rotate the crown or double click crown for the new options.

https://apple.com/feedback