I'm sure this has been debated before......

I have an aging asphalt (black top) driveway and I am thinking of coating it
with driveway sealer (whether by myself or hire someone to do it).
Does this really do anything for the driveway other than make it look
cosmetically more appealing and perhaps fill in any small/minor cracks? It
would seem that this would only be more cosmetic than anything else. The
need would arise maybe 2-3 years down the road to do it again, or have the
driveway repaved.
The brands/types I've seen appear to all be basically the same, lasting
anywhere from 2 to 5 years. Some have a sand mix supposedly helping the
dried surface be a bit more coarse an making the surface not as slipper on
rain/snow for tracktion. And why are they all called 'airport grade'?

Thoughts?
Thanks,
Wally