It is because I believe that harm was done, but also because I am a privacy nut myself, that I am trying to, for my own sake, characterize how I should approach sending emails like this in the future. The study may not go on, but individuals still will send these emails as long as CCPA/GDPR exist. (Just to add some color: It's my anxiety which is causing my to want to delete everything from the internet. If there's minimal info about me online, I can rest easy. It's why this is a throwaway that I will abandon shortly.)
Reading everyone's thoughts is what changed my mind. I now understand to have underestimated the emotional and legal effects CCPA/GDPR requests could have on small website operators, and will be more judicious in the future (like this study should have been) in pre-filtering and my wording. Reactions like kstrauser's (elsewhere in thread) were initially surprising to me (perhaps because of the faceless nature of the internet), so I hope you take my about face as genuine.
Where do you think this balance lies? I still believe consumers, in general, should have right to ask those with their data about their processes; to give it to them; and, to upon request, delete it. And further, in general, I think these interactions are the kinds of things that researchers might legitimately want to study. I found your other comments to be thoughtful, so I am curious what you think explicitly.