You've definitely got the basic concept of giving them a slurry/mash to live and burrow into. I have no idea if it will work with those products though. lol I'm not sure if some kind of fruit/veggie is essential to their growth or just a convenient moisture additive for the grain.
My only thought would be this -
1) The additives powders are great, but why would you spend extra money on them when using baby food to grow the worms would be much cheaper? I can see if you fed them special stuff a day or two before giving them to your dragon to gutload, but just to give them to eat while they fatten up seems harsh on the pocket book! I use additive powders for my feeders as well, but they way I have mine set up is that the bulk of my insects get table scraps and cereal, and as I take them out of the "bulk tank" and into my "hey, you're going to get eaten this week" tank, there is higher quality food in there that includes any additives so that I'm sure what I've paid good money for goes -into- my dragon and isn't just used to help the bugs grow. That's just how I work it though! I'm on a super tight budget so I try to make every thing count.
2) Unless you are using a considerable mount of powder, you're really just wetting down bread with water. This seems to be another argument for baby food.
3) Unless you are mixing your bread with something else, you don't need to grind it down. I just did mine that way because it was stale and I was mixing it with oats.
I agree with you that keep them does seem to be much more of a PITA then other feeders. This process is just optional though, you can always just feed them as is. I think because they are so small and a bit pricey that people decided to fatten them before feeding to increase cost effectiveness. When I lived at home my mom was very critical of the time I spent maintaining my critters as well and tried to limit anything high maintenance. As long as you do the work yourself, hopefully it won't be a problem for you.
Alfalfa extract and bee pollen are two really, really great products. I would use them in such a way that they are going directly into your dragon to make sure s/he gets the best benefit from them. I use bee pollen as well, and give my dragon a blueberry or piece of mango (his favorite foods) a few times a week with some on it, or in a bit of strawberry puree. He's got a bit of a sweet tooth and loves fruit, so it's a nice treat for him and I can regulate the amount of supplements he's getting in that way. Again, that's just how I work it and I'm sure opinions and methods may vary!
I think in the end, worrying too much about one kind of feeder to putting yourself through a lot of hassle is not the most effective use of time. Providing a balanced diet with lots of variety is going to serve your dragon just as well, if not better, as slaving over the "perfect" feeder food, and save you headache as well. Remember, any time that you don't spend fussing over fiddly insects can be spent with your dragon instead!