The allure of riding trees is that it's very challenging and extremely fun if done right. Conditions and terrain also have to be right in order to really experience trees the right way (has to be fresh to semi-fresh powder, with moderate to steep slope).
From the perspective of a beginner, tree are a pain in the ass because you are just sticking to simple groomers and having fun with that. As you progress however, groomers suddenly become boring and you want more and more challenging things to ride. As you gain more board control, making quick decisions and sudden turns allows you to tackle trees properly rather then just heading into a glade and going "Oh Shit!". Once you get good enough, you can spot a glade or open forest and bomb through it, banking turns around trees and bombing through tight spaces.
For me theres nothing quite like it, trees are pretty much all I ride if I can help it (my mountain has at least 1200 acres of ridable trees). It adds a very technical element to surfing pow, making pow that much better.
I also love trees because they hide secret stashes of powder most people are too scared to get