We did change the default in v12.0 for this. It seems like people are divided on whether they more frequently add to projects or not. We have a setting to control the default state of "Add to project" on the "Save As" dialog: Tools > Options > File Options, Save tab, "Add file to project upon Save As".
Maybe we should change this to "Add to project by default" and have this control all "Add to project" checkboxes. This would then affect "Save As", File > New, creating new files through Code Templates.
Let me know what you think.
--Scott