Himu: Sure, Hallmark card life lessons and Jay Leno gags will always have an audience. This stuff would be passed around by chain email if we didn't have other outlets for it. But the nature of Twitter (character limit, follower count, Tweets being publicly visible) makes it especially suited for that style of content.
Which isn't to say Twitter's pointless (as a sports/politics nerd, getting the instant feedback on events from certain pundits is always nice), but it will always foster a certain type of humor (which can be done well or poorly but either way just isn't my cup of tea).