There isn't any way to do that out-of-the-box. In theory you could extend the edit UI but I wouldn't recommend going that route as you'll have to replace/extend key components in the CMS.

From my perspective required fields should be things that are absolutely needed for the content to make sense and function and as such they tend to be limited to types such as PageReference/ContentReference, integers and the likes. When that's the case and there's only a few fields I think it's pretty obvious for editors that this is a step needed in order to create the page and that they will be able to work with the "real" content later.

If on the other hand things like main body text is made required I think it quickly becomes confusing for editors, not to mention that they can't edit it with preview support.

So, my advice would be to use required only when it either helps editors to remember vital properties that aren't obvious and for properties that are needed for technical reasons.

My 5 cents :)

Thanks for the quick reply. Hmmm ... I realize when I read your post that I since the time with CMS 6 has begun (ab)using "Reuired" slightly. I understand what you mean and I agree with you completely. I just have to consider and get rid of the bad habit.