In an effort to combat this, Riot Games has added a tutorial mode called "Battle Training" to League of Legends.
I was able to preview the mode last week and you can read my impressions now.Now, DotA games aren't for everyone, but they can be a lot of fun if you learn some basics and get some good experience. While we all wait for Valve's Dota 2, I recommend trying out League of Legends and its Battle Training mode. It's free to play, though the game does have a plethora of micro-transactions.
If you do decide to give it a go, add me to your friend list in-game. My account is "empathe" and I play every once and a while. I'd be happy to help out some new players and I'm sure other Shacknews members will do the same. If you're more hardcore, you could always try out Heroes of Newerth, which is likely to be much closer to what Dota 2 will be.