About half of the fiber in beans are soluble fibers, which are actually beneficial (along with some resistant starch), but the other half is insoluble and more difficult to digest. This is why traditional beans are soaked and fermented - beans are notorious for making you have bad gas because of digestion difficulties.
The protein content of beans looks great, until you realize they are almost all incomplete amino acid profiles and about 45-60% of it is actually bioavailable, which varies from bean to bean. That means about half of the protein in a bean can't even be absorbed by the body. You'd have to eat twice the protein in a bean to equal the protein of a whole egg in terms of availability to the body, and then you have to factor in that the protein is incomplete in legumes whereas egg protein contains all essential amino acids.
They're relatively low in micros vs the phytate content (hence the sprouting, soaking and fermenting traditionally) as well.
It's cheap, flavorless filler. You could maybe make some low calorie black bean brownies out of them for a treat without a big impact on weight loss goals, but aside from that, I don't see the point. I'll admit, they sound alright.
1 (15 ounce) can black beans
3 tablespoons oil
1/2 cup cocoa
1/2 teaspoon baking powder
1 pinch salt
1 teaspoon vanilla
3/4 cup sugar
1/2 cup milk chocolate chips
Black Bean Brownies Gluten Free) Recipe - Food.com - 418692
Although I'd skip all that sugar - there is probably enough in the chocolate chips - and whatever's lacking I'd round out with stevia.
I haven't bought beans for 2 years. The only time I've eaten them is the handful of times I've gone out to Mexican restaurants because white rice and beans come with everything. I won't lie, they're delicious when made right, but they're not in my pantry at any given point. Truth be told, they are pretty filling per calorie and would probably aid weight loss if all you about is weight loss and not overall health. They're not gluten grains or oats - they're definitely an order of magnitude better - but still pretty low on my priority list. I put my personal health as #1 beyond strictly weight loss, so that's why I don't eat almost all grains and beans.