Not every dragon encounter will be a winning fight.
That said, most of my character concepts are melee or magic. And Magic has a relatively short range in comparison to how far the dragon flies around to nuke you. So it will be frequently frustrating I'm sure.
While that is true, I *was* winning, until the dragon left to go heal himself where I couldn't reach him, then he came back at full health.
I could have walked away, but the idea of spending that much time, materials and energy into a fight only to not win the fight was frustrating, especially because I had almost won the fight.
Fast travel wouldn't work either while he was "nearby". So, I did at one point start climbing down the mountain, only to have him come after me while descending. I had almost defeated him that time as well before he evaded my wrath. It was only the third time I went running down the mountain like a mad man that I was able to get out of range to fast travel.
Oh, and some of the Apprentice level destruction spells have a very good range, practically infinite as far as I can tell. It's only the streaming ones, such as flame and sparks that have a limited range. That being said, a bow and arrow is probably easier to hit a moving target at a distance, due to charge up time and time of flight of the projectile. It is rather annoying that the spells obscure your view of the target and cross-hair, especially when the target is smaller, as with long distances.