Again, why do you even need a hypothesis? If you had access to millions of (sanitized for privacy) patients' medical records and genomic records, you could provide the proper medical treatment for someone without knowing how it worked or why by essentially "brute forcing" the correct course of action out of the countless permutations previously tried in previous patients. Hell, needing to develop a hypothesis for the causal mechanism for how a particular outcome worked might actually slow down or impede scientific progress in the future since understanding the "why" of something might become the least important part of science.
And why do you assume this is actually the case? More than one person has already informed you that studies proceed in various ways--and many times essentially as you suggested. A hypothesis isn't always an explicit question. It is sometimes a broad target that points towards a region (in a local area of the genome, for example), that might be of particular interest to that specific research group.
NCBI has open resources of thousands and thousands of genomes where anyone can search and find hits for their particular region of interest. If their investigations lead them to certain hits, they might begin targeting those hits with various tools that have been designed and used for the last couple of decades--say knockouts or knockdowns--shutting off the function of that gene to see what happens.
No one that I know wastes their time trying to come with a "why" before they find a significant effect. That is often the far more complex question and once you begin down that path, it can lead towards many branches and perhaps several dead-ends that end up being irrelevant to that particular project. Nevertheless, data tends to get published in that process and if some research group somewhere else finds tangential relevance that never applied to the first research group, you might end up with a different class of "whys" that are now more useful in a different field.
You assume this is a process that isn't already in play but that if it were, we could somehow develop medicine for humans by cutting out some perceived bullshit in the process. First, that is less of an issue with the progress of science than it is on standards and ethics that are necessarily in place to prevent open experimentation on human subjects. In some cases, I do wish we could take more risks in this way (it's not like Pasteur ever gave a fuck about that), but it's a very different world of understanding now and the comparatively simple mechanics of how vaccines work next to genomic tampering--more and more of a minefield of unknown consequences the more we learn--medicine simply can't work that way.
I think the public is most often confused about how slow the realities of advancement are because they are lead to believe through popular entertainment that this is a quick process that takes one singular brilliant mind a weeks-long montage in a poorly-lit-yet-highly-stylish gun-metal colored lab to unlock all the mysteries of an impossible disease and perfect the perfect pill.
That simply does not happen. The most effective cures that we are aiming for these days--direct genetic targeting, either as a replacement/blocking or as a specific target for medicine delivery--are never going to be a key + slot = open door approach. It's more like key+slot = dozen open doors, 3 of which might be promising, but also some scattered hidden booby traps like spike and flame traps in that same room.
Removing those booby traps and eliminating the false doors within the genome (which is more accurately an issue with the transcriptome, the epigenome, and hosts of siRNAs, picoRNAs, blah blah blah) takes a very long time.
It's frustrating, too. Biology simply does not happen on paper. Living systems behave quite differently from non-living force-force interactions that are almost completely driven by pure math and, well, can and do happen on paper.