we dont most of the time, thats why data is pseudonymised. it can be reversed, via a third party with controls, for appropriate uses. GP records provides a very rich history of conditions, with treatments and comorbidities over time, valuable to good research.
most valuable yes. I think what's concerning is the opportunity, which doesn't currently exist., for the less scrupulous 'researchers' to just bung a few quid and get all the access they need for all the wrong reasons. A cynical opinion brought about with extremely good reason.
In extremis we have governement which long since sold its soul to the devil, selling off our NHS then selling off our data so huge swathes of the population can't even afford to buy any care.