I kinda feel like mealworms get a bad rap.
If we take a look at the nutritional analysis provided by grubco for their insects here
http://www.grubco.com/Nutritional_Information.cfm we can make a few interesting observations.
Firstly, that nutritional content in nearly all areas appears to be in the middle between crickets and superworms. For most figures (moisture, protein, calcium and phosphorous) crickets scored the highest, then mealworms, with superworms scoring lowest. For fat, superworms scored the highest, then mealworms, then crickets. For fiber, superworms were significantly higher than crickets, and mealworms scored the least.
Diet of the insect will significantly effect its nutritional quality and content.
We can see a few other sources for comparison on this site here
http://chamownersweb.net/insects/nutritional_values.htm
Here we can see grubco's analysis along with analysis by argentina birds.com and reptile rooms forum which are not in agreement with some of the figures provided by grubco, presumably because the insects analyzed were fed a different diet. Also provided are a few different analysis, such as calories and mineral content and carbohydrates.
Interestingly in these analysis, sometimes mealworms scored very close to superworms, and sometimes slightly lower, in disagreement with grubco's analysis. Again, most often they scored in between superworms and crickets.
From these scores, it becomes very obvious that they do not have "little nutritional value". Even the claim that their exoskeleton amount is less than supers in proportion to the worm becomes a little "iffy" if I understand the figures (I am guessing figures relating to moisture content, ash, and phosphorous and possibly fiber would be relevant to the amount of hard chitonous exoskeleton which would presumably have greater amounts of ash and phosphorous and fiber and less of moisture- yet mealworms are not scoring the way we might expect if this is correct and if their exoskeletons were a greater percentage of the insect compared to superworms).
Also in his book on the panther chameleon, ferguson outlines his methods for keeping and breeding chameleons over multiple generations in his lab, and explains that he selected mealworms in addition to crickets because he found that when fed the exact same diet, the analysis done on his insects had mealworms scoring higher than crickets for calcium content, so he decided to use both insects for his chameleon diet.
Sure if you raise them on wheat bran or oatmeal they are probably going to score similar to grubco's analysis. Which is still OK- nutritional quality will be somewhere between a cricket and a superworm.
But I don't feed my mealies that way. They can be fed any dry stuff you would feed to crickets or roaches and they will breed and thrive in it. Plus a bit of fresh veggies (small bit that is gone in a day or so or you will end up with dust mites). When fed this way, they should have higher calcium content than crickets fed the same diet, if ferguson's analysis (professionally done) was correct.
At the very least they can be fed whole wheat flour instead of wheat bran- bran has much of the nutritional content removed compared to flour.
Mealworms are not useless, they are the easiest insect to breed, large scale breeding can be done in small enclosures (I produce several thousand per week in small tubs only a foot or so wide and a bit longer and perhaps 6" deep). Their nutritional analysis has been shown to be midway between two commonly considered useful feeders (crickets and superworms) and can be further enhanced by feeding a high quality diet rather than oats or bran.
I've used them for many years as one part of a varied diet (usually I offer 1 feeding of mealworms or 2 feedings very occasionally for lizards that have a daily insect feeding, per week).
edit- another link that is interesting reading with more in-depth analysis of many species of insect. Mealworms appear to outscore superworms most of the time on this analysis, but maybe they were fed very differently and the supers were not as well fed.
http://www.organicvaluerecovery.com/studies/studies_nutrient_content_of_insects.htm
Can we please stop repeating the notion that mealworms are poor nutritionally?
Or show me how my conclusions are wrong with something other than anecdotes?
and Nick sells alot of them - he had all the yummy weird food chams love 
I now breed over 23 dif/ feeder items , and as odd as it sounds, I do enjoy the bugs too 
