Why is it now...
everyone uses the term "UFO" meaning "flying saucer of an alien nature"?

Unidentified flying objects are just that, it does not mean they are from another planet. It just means they're flying about and you have no clue what they are.
( vix0r was not Matthew on, Mon 7 Jul 2008, 17:00, 3 replies)

When they land they are just unidentified objects

( Hankster, Mon 7 Jul 2008, 17:23, closed)

And when they're identified, they're objects.
And if they're laying on the ground, then they're unidentified subjects. The ground is the object.
(sabre-tooth monkey, Mon 7 Jul 2008, 17:31, closed)

probably
because it's a term popularised by modern media and those without an explicit interest in the subject can remember it. Other than that, aren't they all UFO's until reliably identified as planes/weather baloons etc so the 'alien' ones remain classified as UFO's.
(Greencloud Wanted to go fishing on, Mon 7 Jul 2008, 17:32, closed)