I understand why you can't have Reed Richards cure cancer or AIDS or have any powerful superhero make peace in the Middle East and end world hunger in one big swoop. But why, oh why, don't we see more examples of authors taking advantage of a simple way around this problem - show the hero slowly chipping away at a huge problem that's often over-simplified, and the problem will still exist and the fictional world will still resemble the real world, but the hero appears less useless.
Example: It's great to ask, "Why can't Reed Richards (or any other fictional Omnidisciplinary scientist) cure cancer?" But "cancer" is actually a very broad term for many, many different kinds of specific diseases that have different effects, vary in treatment and survival rates, and of course have all kinds of different causes. Even the term "breast cancer" can refer to several kinds of tumors, and the term "breast cancer" doesn't really tell you anything beyond the area of the body afflicted. Not to mention that no matter how much of a genius Reed is, any cure he comes up with has to go through clincial trials, FDA approval, and marketing before it does anyone any good. This trope could be averted by a scene where someone could sarcastically ask Reed this very question, only for him to cheerfully answer that his serum for treating (insert specific medical name for aggressive tumor here) has just hit the market and his cure for this kind of lymphoma and his treatment for this kind of brain tumor and cure for this kind of leukemia and a possible Hepatitis C vaccine are in varying stages of FDA trials, and the mocker would have egg on their face and Reed would look less, well, useless. Cancer would still exist, it would still be a big problem, and the fictional world would not be drastically different from the real world (other than, you know, all the superheroes running around) but it would look like someone was at least working on it.
All right, but he could work on cures for other diseases, like HIV. Or Autism. Or Down Syndrome.
This was mentioned in an Indestructable Hulk comic, Tony Stark said, "there are some Cancers I don't know how to cure yet".
Caveat: We do see this kind of thing happen in fiction, but not nearly often enough in my humble opinion.
Your solution might work for some things but not for others. For instance, Reed Richards clearly has access to his own clean and renewable energy sources to power all his fantastic inventions (the man launches space ships from his office building for heaven's sake!) yet he never offers this technology as a solution to the energy crisis. Speaking of which, Reed Richards has a personal space ship. That he built IN A CAVE! With A BOX OF SCA—*cough* sorry. Anyway, he has his own personal space ship and makes regular trips across the solar system and occasionally the galaxy. Why has he not used this to re-energize the space program?
Let's not forget that Reed Richards could probably duplicate Dr. Doom's burn victim cure device.
Reed is rich, some things may be expensive to mass produce. Not to mention a lot of geniuses spend very little time on Earth in the first place. Tony Stark and Hank Pym have less of an excuse though.
There's a couple reasons: It's easier for a writer to imagine his own world and just drop a super-smart dude into it, than to pull all the threads to see what sort of actual effect he would have. The fact that Alan Moore actually did this with Watchmen is why I liked it. Secondly, if the writer actually did follow through with this, after a while you run the risk of the comic book world becoming so alien that your readers lose their connection to it. A world with abundant clean energy, no cancer / AIDS / Flu / etc, peace in the Middle East, w/e is going to have completely different problems which most won't relate to.
Consider the time that passed in the comics since the first man in space (10 years, 20 maybe). Now look at the technological level of the Marvel Universe's Earth. The super-scientists of the Marvel Universe must have an influence on their world for it to be as advanced as our own in a third or a quarter of the time.
I wonder why someone deleted the same kind of remark I had made on the main page.