Well, many little LEGO environmentalists will tell you that its due to illegal logging, and that the logger minifigures then build fake, brick-built trees so nobody will notice the one-piece trees are gone. Don't listen them, this is a pack of lies. In reality its just the LEGO company being stupid. The LEGO company does dumb things, this is one of them.

I miss the classic trees, they are great for brickfilmers who are lazy or just want to build a set in a rush. I have a few from my mom's old collection. They are pretty useful, especially when just putting them in the background.

I actually kind of prefer building my own trees. The classic ones don't really have any studs or customizability.

On Pick A Brick you can get a ton of the classic trees. That's how I got mine.

I tend to like custom, brick built trees, so that I can make them as large or small as I need, or any color I want. However, I do like the one-piecers for background fill (if it's out of focus), or, as was said, for manicured lawn type of settings. The one bad thing about custom built trees, is that they tend to take a lot of pieces and leaves, which cost a fair bit of money, for a substantial amount of trees...which is why I can only make about 2-3 of them at the moment.

2nd place Darkness and Light entry: The Tree
Behind the Scenes