Here are my 2 cents. I think the entire course is amazing. Its kinda yes and no. Characters do help with story telling even in the concept phase. You don't have to be an amazing character designer. The characters in your scenes can be npcs. For example, if your doing a village, you would want some characters in the shot to really sell the village idea. They don't have to be the main focus in the scene as that is up to the environmental assets. If you design a market, it needs people there to buy stuff.
Learning the basics of characters I think is key here. You don't have to be amazing but understanding how they'll be in the space you create is important.
The characters can also be used as a meter of measurement in your scenes. When you really want to show off the scale of something, human characters can work nicely for that. Of course characters don't have to be in every scene you create. Some concept artist don't have characters in there scenes at all.
If you can, find artist you like and look over there portfolios. Try to DM this same question. Don't be bumb'd if they can't respond back but you can try.
Hope this helps.
