I think this is a sign that you are not designing maintainable systems in the first place. I work on reasonably complex systems where significant changes to a feature do not tend to cause huge structural changes like you describe, and where the vast majority of tests tend to remain unchanged and help detect regressions. It is entirely possible, with the right design. And in my experience, developing a comfort with TDD will help promote that kind of design.

(Edit: I want to clarify that this is not meant in any kind of a judgmental way about your work or your talents, I'm sincerely trying to help identify issues so that you can hopefully become more productive and more confident in the work you produce.)