On Wikipedia, should people's days of existence have pages, not just general histories?

It might be tedious and difficult to achieve, for no clear benefit.

It would be difficult to achieve. The system would be at risk of overload.
Do you think the majority of people would want to see Wikipedia do something like this?

I do not think so.

Any major incident in a person's life (famous or otherwise) that has (worthy or otherwise) a wikipedia entry will most likely already be documented. If there's something specific (day 10950, he/she made pancakes that were uber amazing) that was noteworthy then you can add that to the wiki page yourself.

What about the idea of a page for everyone on Earth? And on that page could be details such as perceptions of nature, or favourite movies and why, or sources of depression?

What about 100 pages for each second? About each cell of their body? How far to pursue this? Why?

That still wouldn't match screen names to real names, addresses, and so forth.

What makes you think everybody on earth wants a page?
How would you know what is on that page is really the truth?
My family and friends know about me - the rest of the world does not have to.

I think it would be helpful if everyone on Earth was if not asked individually, at least represented by some global initiative.
Another initiative I believe in is the UN stating that each individual is the Universe; I suppose this initiative would be alongside it.

Do you have a perception of nature that you want others to know about - or if not a perception per se, an experience of nature that inspired you?

Why should the UN state such a crazy thing?

Because reality is dependency, and the universe as an identity representative of dependency is better than any other identity that's representative of dependency.

You gonna pay for it?
Wikipedia is always trying to raise funds to pay for servers, storage and so on. I think I see a fundraiser in your future. Better get on it.