Some anglers look (especially fly fishers) down on those that use live bait to catch trout. They consider the practice sort of like cheating. The use of live bait, to some, requires less finesse. These same anglers will argue that it takes more skill to fool a trout into taking an artificial fly or lure than it does to dangle live bait in front of trout.
While I can agree that it sometimes does take more skill and finesse to get trout to strike an artificial bait, I also believe that the use of live bait takes a bit of skill.
For one thing, it doesn't matter if you're using live natural baits or artificial, you still need to have the skills to figure out where trout are holding. It also takes a bit of know-how to properly hook your live bait and present it in a way that looks natural to trout (or they won't strike).
However, one of the downsides to using live bait is that trout will often swallow it making it difficult or impossible to remove the hook. This doesn't normally happen with lures.
If you plan to practice 'catch and release', you should avoid fishing with live bait. However, even when fishing for dinner there are times when you may need to release your catch (like when it's too small to keep). Fishing with live bait in this situation is perfectly acceptable, but you still may face the problem of having the fish swallow the hook.
One way to combat this problem is to use single barbless hooks (which are easier to remove). You can also pinch down or file the barb off your hooks to make them easier to remove from fish.
In situations where you can't remove the hook without causing internal damage to the fish, it's best to clip the line as close as you can to the hook without trying to remove it. Trout do have digestive enzymes that can dissolve the hook over time (unless it's stainless steel).
Whether you choose to use live bait (worms, minnows, etc.) or artificial lures, understanding the common problems associated with each as well as how to overcome them will make you a better angler while preserving trout fisheries for future generations.