The problem with .psd’s it that these files are designed in Illlustrator. They can be exported as a .psd, but then you lose the ability to edit the text anyway. At that point you may as well be using .pdf’s.
If you have a specific file or three you need in .psd drop me an email and I can convert it for you.
It is something we could look into for all the files, but is much more time consuming up front as all the type would need to be re-entered in Photoshop so that it could be editable later on. File size is also a problem with .psd’s. For example I just tested a file that is 22MB in Illustrator (which is WAY too big for my liking). After exporting it as a .psd it was 66MB.