What does an unabridged dictionary provide?

I can think of three things that an unabridged dictionary could provide:

1. A whole load of extra words you never knew exist (ed) and will probably never need (unless you play Scrabble*).

2. Extra details like the origin of words (etymology) as far back as they can manage to find in print, nevertheless mostly on guesses.

3. Volumes are bound to fill an otherwise empty bookshelf and it looks good. (Gaud, there must be another word for that ...)