When we are making a stollen from white flour, we make the dough, develop the gluten and then, only at the end do we mix in all the extra stuff – fruits, nuts, and whatever. If we included all that extra stuff in the initial mix, the gluten would not develop properly.
Whole wheat flour has a lot of extra stuff in it – stuff that can inhibit the proper development of gluten.
If the texture of ordinary 100% whole wheat is simply not acceptable to you or your loved ones, there is an arduous path to a fluffier loaf.
Sift out all the stuff, make the dough, develop the gluten, and then fold all the stuff back into the dough. You will need to carefully, fully hydrate all the stuff. It needs to be hydrated, without holding so much water that the extra water spoils your dough. And the stuff needs some extra oil or fat. These days, I add ~2% oil (baker’s percentage) to my “bran soak”.
This is more work, but it does make 100% whole wheat bread that is somewhat more like some conspicuous consumption Artesian product. On the other hand, I like good old American whole wheat bread. I like breads made from “high extraction flours” where the bran is simply sifted out of the flour, and I like bran muffins and extra bran in my morning porridge. There are many paths to good bread.
I really have not decided if I like the slightly more open crumb structure (it does not hold jam, mustard and other juices as well.)