Retro51

I jog and walk and do other exercises (jump rope, for example) often. I try to jog on places like the Trinity Trail from Benbrook, or up by University in Fort Worth, or Forest Park by TCU. I also jog in parks, running around the trees. My experience running on hiking trails has been limited, but I see it as another fun thing to do. I have wanted to go on a trail running excursion, but usually wind up biking in that case. It depends on your goals - if you're mixing jogging and exploring, it's a good option. If you are more interested in the hiking, or going with non-runners, you just hike. Also, if you have to pack in your gear, you would just hike.
If you want an option to further your exercise, and mix it with hiking, you might consider Nordic Walking or hiking with HeavyHands - Google either one for more information. I walk/jog/exercise with HeavyHands almost everyday, and have used them when hiking. You get many of the same benefits as jogging, without actually running. You get some benefit with Nordic Walking poles, with the added stability, especially up/down hill.
BTW trail running is usually one of the more difficult activities, because of the hills and rough terrain, so they are due respect. They obviously are out to enjoy nature, since otherwise they would just run on streets or a track.