You shouldn't let this drive you crazy. Most people use Photos' Edit Markup to do this:

Use Markup on your iPhone, iPad, or iPod touch - Apple Support
Putting the date on a picture could be a good feature--but I see lots of complications. Where do you want the date on the picture? At the top, hiding some of the picture, or somewhere else hiding another part? In the exact middle of the picture? Or do you want the picture to be smaller than full screen, with the date in a white margin at the top? I'm guessing different people might want different things. Markup lets you choose all these things, but it means you have to do it for each picture.
There may be 3rd party apps that could help, but I'm not sure.
If you can think of something that would satisfy lots of people, and make no one angry, you can make suggestion here:
Feedback - Photos - Apple