A lot of misinformation being tossed around, which is perfectly normal considering it's the Toribash forum.
Remember to take everything with (more than) a grain of salt.
We really need to be humble enough to understand that the core question will take a lot of time to be answered to.
The standard of care for even the most basic common diseases that you can think of still changes extremely often to this day, and will continue on doing so for a long time.
Making broad claims about it being harmful to x and y system, or better than every medication currently available for w or z indications, is something that you can not possibly be certain of.
People in the medical field won't make that kind of claim, specially because they understand that what is "best" varies wildly with the details from case to case, and the guidelines we follow are updated regularly since so is the scientific knowledge about every drug on the market.
The approval from the FDA and EMA (the agencies that oversee all of this stuff in the USA and Europe respectively) isn't even the end of the line, the "yep, it's safe boys, we did it", as it is sometimes portrayed.
After a drug is approved it is still tightly monitored and studied, and some drugs were actually only deemed "unsafe" after being sold all over the world,
years after their introduction on the market.
In my opinion, in the near future we'll see marijuana use legalized (to some extent) in a sizable part of the globe.
This will enable it to be studied to extents far greater than it has been so far for a multitude of reasons.
Only then will we actually be able to have a better grasp on its public health implications on a variety of time-frames, and maybe leading us to revisit the question of legality (a VERY big "maybe" on that last part though).
As for specific medical uses, it's honestly naive to think pharmaceutical companies will crash and burn because of marijuana.
It's a business opportunity and some are investing into it already.
The huge amount of regulations put in place for medical substances mean that these companies even have an hedge into this market, with the infrastructures and know-how already there.
Finally, its active principles (fancy term for the "its important parts") being a medical option is being studied in many different settings individually, and you won't get a proper broad answer (well certainly not now, and certainly not on the "should").
If you're extra curious you can check out the clinical trials that are being hosted right now over here
https://clinicaltrials.gov, by typing in the active principles.
PS: Come on guys, it's not a science forum, but remember that using your own anecdotal evidence can't be taken seriously. Not every human is the same, and what happened with you or your friend can't be generalized to the whole mankind.
Also everything that you eat and breath is a "chemical". Nothing is inherently safer/better because it is either produced in an artificial manner or not, and that is unfortunately one of the most dangerous assumptions people make
Sorry if I ran astray sometimes. I'm very tired and tried to cover a bit of everything I felt was important in the thread.