If historians haven't been putting this archive to good use, it's certainly not because of a simple lack of scans, and the Vatican is likely to not give easy access to the scans for mostly the same reasons they keep people out of their archives.
Certainly buying a plane ticket to Rome isn't the end of the world, so historians put the archive to as good use as they can. But they, the people long trained to make use of delicate ancient document, are dismissed as some sort of backwards tribe that are not fit to be labelled "modern scholars".
They keep people out of their archives because things are fragile and poorly organized. Don't underestimate how difficult (and expensive!) it is to keep these documents preserved. I've had pages fall apart in my hands and the document was only from 1714. I was taking proper precautions, too. And, I should note, the documents were adequately preserved according to the standards of the time. The Vatican only wants to let in people who have a good reason for being in there. Fishing expeditions-- especially by independent researchers-- are not permitted, because they can damage the documents. That creates a weird chicken and egg scenario, because it makes it very difficult to find new topics to explore. Also, it means that you won't be allowed to use the archives unless you're certain that 1. the documents are there and 2. they are instrumental to the topic at hand.
Digitizing the documents will change all of that. It's a lot less error-prone and destructive than creating microfiche and it yields quite a bit of other benefits, like indexing. No one, least of all the Vatican archivists, have a complete picture of the contents of the library. Once they have those scans they'll want to release them because it will help us understand a great deal about Christianity and post-Roman Europe. The only limitations I can see are those that other libraries have put in, such as forcing researchers to view the documents in the browser, as opposed to downloading them. That's what Oxford did with their collection of ballads (whether they still do I don't know). That's annoying, but they reasoned that it would keep people from taxing their servers by downloading the entire collection wholesale.
And I'm not sure what you mean by referring to trained archivists as being dismissed as some sort of backwards tribe. A great many history programs have archival (i.e. "library science) programs and training for their PhDs.
I think I qualify as a legitimate historian in this situation (I actually did buy a plane ticket to Rome last year and spent a week looking through physical texts at the Vatican archives). I'm thrilled by any efforts to digitize and OCR this texts and so is everyone else I know who does archival work. So I don't really know where the tone of dismissal/cynicism I'm picking up in your posts is coming from.
As anyone who does archival work will tell you, one of the biggest problems is the "too much to know" issue: it's basically physically impossible to look at every relevant page of every relevant text when you only have at most a few months to a year to do your field work. So aside from the convenience aspect of being able to double check your work without flying back to Rome (or wherever), OCR also offers a qualitatively different style of research that lets you trawl for words or phrases across a very large corpus. That's super valuable for doing intellectual or cultural history, or biography.
One big practical reason the archive requires special access is that 1200 year old paper documents are fragile and require special handling to read. If the Vatican allowed everybody to come in and finger through them, they would be easily damaged.
Furthermore, I suspect required travel to Rome has prevented a lot of people from using the archives.
> But they, the people long trained to make use of delicate ancient document, are dismissed as some sort of backwards tribe that are not fit to be labelled "modern scholars".
I don't see anybody here making that claim, and I don't know what it has to do with the Vatican archives.
Are you saying it's better to keep these documents locked in the Vatican instead of digitized and easily available online to everybody?
Surely it's better to have digitized versions rather than having a million people thumbing through delicate ancient documents?