If roots are exposed for long, especially to both the sun and to dry winds and or if there is a good amount of root loss/damage you can have a real problem on your hands, plant death may be one of them, but normally if the root exposure is short term and not exposed to much if any direct sunlight and or dry winds plants should recover.
 
Just losing or removing the dirt from roots is not a problem. At times a bare root transplant is the best way to go. Of course you want to remove all the roots in a rootball if possible and then rinse off all the dirt with a hose or be repeatedly dipping the rootball into say a bucket of water but either way it is not like losing or removing dirt from roots is something tragic or deadly unless like I said one or more of a few unwanted occurrences are involved.
 
But what you experienced is why I never repot plants
. never
.. NEVER. I always start my plants in the largest size pots that I will use for the grow and I always use pots that are larger than most people on sites like this believe are needed.
 
Every time you handle a plant you risk damage and stressing the plant so if that can be avoided why in the wide, wide world of sports shouldnt you avoid it?
When you start out in small pots and then bump them up in size each time the plants outgrow the pots you not only risk damage while handling the plants but also stressing the plant by transplanting it but you also risk stressing the plant due to allowing it to reach a root-bound condition.
 
As soon as roots begin to circle a pot the plant is then to some degree stressed and the worse the circling gets the more stressed it is. If you wait until you have a tight rootball and then repot unless you score/cut the rootball before putting it into the new soil/larger pot the roots will have a very difficult time growing down into the new soil/larger pot and will for at least some period of time continue to circle and intertwine.
 
If your plants become root-bound before you transplant, or if you grow in pots that are to small and they become root-bound you risk stunted growth, stretching, smaller and slower bud production, you will need to water too often, the plants are easy to burn even with a low percentage nute solution and you very likely will experience wilting.
 
Indoors I never use anything smaller than 5-gallon pots and normally use 7-gallon pots and if I grow outside on my deck I use 15-gallon pots. From planted popped beans to harvest my plants live their entire lives in one size pot and by doing so I avoid myriad possibilities of problems.