Yeah this gets me everytime too, even after years of elektron experience. Its a strange descision. In 99 out of 100 cases, you would want a pattern to have its own kit. If you want to share kits and have to perform a few button presses that would be ok.
Now the default is working with shared kits, and the exception is a kit per pattern. Should be the other way around. They will probably never change that because they would have to change it on all machines except the OT.