Well, that really seems to be a very hard problem to me.

Tables for instance get quite complex pretty fast -- joined cells, text alignment, etc.

As for a format which -- not plain text, though -- that handles this is rich text. It's been around for quite some time.

IMHO the problem is in the difference between presentation and data. One group of consumers want the "data" and parse it, the other group of consumers want to basically have it "look the same in this app as in the other app, and don't make my think."