Betreff: suggestion/ Feedback for Acrobat DC.

If you have a feature request, feel free to use the official form: https://www.adobe.com/products/wishform.html

Deleting elements in PDFs can be very complex, since there can be thousands of them in multiple layers even in a simple looking page or illustration. It really depends on the way the PDF has been created. Acrobat isn't able to distinguish which element might be irrelevant for you or not.