Units like Dragons and Heroes *should never* be facing enemy units unless you are really desperate or involved in a big hero battle. Those units are far too valuable to be in battle. They require lots of cannon fodder up front in order to protect them.
That's a general rule, right. But when it comes to dragons, you can't ignore their maneuverability and their single-unit power. That means that against single-unit armies and places guarded by single units you stand pretty nice chance of winning (82% against HI guarding a +10 city if my numbers add up) and as every good bridge player can assure you - when there's a nice, fat chance of winning, it's prudent strategy not to hesitate and take it . All of it means that you'll rather see weathered veterans using their (especially first) dragon to rush their opponent (I point my accusing finger at you, ChickenChaser ) or to conquer a lot of hard-to-access cities ASAP than parading them across the map in stacks chockful of LI.
@Manukai: don't want to be harsh here, but seriously, you seem so clueless sometimes I start to wonder if it's not feigned for some twisted forum-ish amusement of yours :>