Dan,
Sounds your Burris on the .22 Hornet has their Ballistic Plex reticle--which is the same scope I've had on my Hornet for years now.
Christmas tree reticles primarily appeared as an early solution to shooting farther, after laser rangefinders appeared. Many (perhaps most) were too coarse for hitting small varmints consistently at ranges where holdover was necessary. Which is one reason I have the Burris on my Hornet (its simple little hashmarks work very well at such ranges), but tend to "dial" elevation for shots much beyond Hornet range. It's quite common to shoot some varmints at 500 yards or even much farther here.
One reason illuminated reticles are often used by U.S. hunters are laws that limit legal shooting hours (usually 1/2 hour before sunrise and 1/2 hour after sunset) for shooting "game," as opposed to varmints--along with a general law against shooting game with the aid of electric light. White-tailed deer are by far the most popular big game, and they're pretty nocturnal by nature, and become even more so with hunting pressure during the season. Being able to see the aiming point better at the very edge of legal light can help a lot, and one reason for the self-illuminated Trijicon reticles is they provide that aiming point, but don't overwhelm the view with too much light, as some of the electronic reticles can when turned up too high. (Varmint shooting is another deal. It's often legal to shoot some of them, especially predators and feral pigs, at night with the aid of a light, or even more sophisticated night-vision or thermal scopes.)
