Wanted to provide an update here.
First of all, if you are running into bugs (like all your photos have the same date) please reach out to support. If you’re on mobile, you can shake your device, if you’re on the web, you can use the settings cog.
As for the ability to change metadata on photos, that’s not something we currently have on the immediate roadmap.Dan Davies commented
Being able to modify the date take is pretty essential. I have recently digitized lots of old photo's using my smartphone - obviously OneDrive see's the date as the date I took the digital photo of the original photo. The original photos all have the date on the back so it would be great if I could correct this to have the timelines work. Google Photo's allows this (but doesn't allow tagging, and reduces quality) if OneDrive supported editing the Metadata it would easily win any comparison between the two offerings.