I don't care what you put in a box mix, the chemicals are very apparent. I use box mixes for one thing only, to practice a fondant technique and then I throw it in the trash. My family will not touch them.
I'm at too many events and weddings where the photographer, caterer, guests, DJ, wedding planner, all come to me and can't believe a scratch cake is available. They then talk about the box mixes everyone serves and are the status quo for weddings. They are not enjoyed as much as you all think they are because those that do this weekly know that guests know it's the same cake they can make at home in 1/2 hour for $1.00. Most of the time it is the only option in the market. I don't consider a box mix worth working off. And the plates at weddings usually reflect this too.
Remember brides choose box mixes out of economics too.
So if you can bake from scratch and can find the right market that will pay, you will usually be the only scratch option and you will have that market to yourself, while the huge group of box bakers fight over the same group of brides.
As far as a scratch cake being dry, you just have to find good recipes. I found it helps to have some knowledge of the science of scratch baking. I actually have recipes on my menu that I did not even bake before I added them. That's how in tune to the ingredients you can get. I can read a recipe, know how to change and accurately predict the outcome. Actually the same thing our grandmothers used to do. It was just a domestic chore, now we call it art.
I look for a lot of fat in a recipe. I also like buttermilk and sour cream over milk. Even though I have butter recipes, I find these need to be watched closely and the customer needs instructions on storage so that it won't get dry. I usually use a fine cocoa powder and add the fat to a chocolate cake. But again, I have some that have chocolate in the batter. Because these are solids, the batter must be able to handle that ingredient at room temp and not dry out, like butter cakes. And with experience and manipulation, my yellow butter cake now gets ultra moist in about 24 hours. I make a lot of cakes flavored with liqueurs. These cakes must start out drier and sturdier in order to accept the liqueur. And the odd thing is that many of my recipes that have brushed liqueurs start out as a whipped egg white recipes that are usually more delicate.
All I can say is that people with great scratch recipes either put in the time to experiment or someone taught them proper method and shared great recipes. My 17 year old daughter helps me and will probably take over this business after college. She has learned proper techniques and has my recipes. She has never known a failure. But I sure have. It's part of the process.