system
Given the following post, respond as if you're commenting on Reddit:
human
[Marvel] Why are governments so focussed on trying to recreate the Super-soldier serum? Wouldn't it be easier to recreate a super powers like the Fantastic Four?

Just send a bunch of astronauts into space, intercept some cosmic rays, and you are done. It works on anyone, gives you a variety of different powers, and doesn't appear to have side effects (apart from occasionally turning into a pile of rocks)

It worked by accident for the FF, but was successfully recreated by the U-Foes. Reed Richards probably knows enough about cosmic rays by now that he could recreate it on Earth.
gpt
In order for a programme that creates superheros to be *really* useful then the process of creation is best if it is reliable and repeatable. The superhero serum was a huge, ***huge*** success, turning a weakling into an incredible person - it also was designed to be able to work on everyone. If it had been able to go into production then there would have been whole *armies* of Captain Americas storming across the battlefields, winning wars easily. 

Now as for why they do not go down the route of cosmic rays, using mutants etc, it's because the changes are seemingly random and powers are unpredictable. Sometimes you'll get something useful, sometimes you'll get a guy who can eat any amount of chilli without needing to drink milk but each takes a vast amount of resource and money to create. 

Mutants (another option from cosmic rays) are also unreliable in their creation and have massively varied power and usages. Each different power needs to be explored, analysed and carefully worked on and this takes time - you want an army and you cannot have hundreds of thousands of different powers which each needs investigating and controlling. Some will need special equipment or training and basically it's a huge hassle. 

Super serum gives you strong and reliable results and no need to special equipment or training. That's what you want in an army. Sure there will be more powerful people out there but you can see what Captain American can do, if you have a few thousand of them then they'll be able to take action against almost any threat and you still have mutants/lucky one offs as well for really high tier stuff in the Avengers. 

Finally, if one Super Soldier gets out of hand it's not impossible to stop them. If, say, someone who controls the weather decides he wants to cause trouble then you have a much bigger problem. 

TL:DR - it is repeatable, regular levels of power and it is controllable.