Why do people leave around time capsules?

Why do people leave around time capsules for future generations?  People in the future aren’t going to want that junk.  You know people actually put floppy disks in time capsules.  What are people in the future supposed to do with that?  If someone left a note on a floppy disk and on a rock, the rock is actually a more relevant way to store data. 

Even if you put DVDs in time capsules, people in the future are still going to make fun of you.  Person from the future, “Look at this guy, he is using an information disk, man life was so primitive before information spheres.”

People put a lot of junk in time capsules.  If you don’t want stuff that’s fine, just throw it away.  But don’t bury the junk in your back yard.  People are usually pretty smart.  But, when people start thinking about time capsules; they don’t act rationally and revert to their basic instincts. 

In the year 2224, the Antique Roadshow will ban people from bringing time capsules on the show to be valued by the appraisers; because by then, time capsules from the 20^th century will have been determined to be worthless for over twenty years. 

The only time capsules that people want to find, are the ones filled with money.  The Egyptians got this one right with the pyramids; instead of filling the pyramids with: musical lyrics, newspaper clippings, or personal pictures, they filled them with gold.  The Egyptians also had a better strategy of only putting part of the time capsule underground and then leaving a five hundred thousand square foot pyramid on top of it, to give people a better chance of finding it.