The value of the paper and ink originals is that they are known to be both durable, and sustainable.
This is not true in the slightest. There are millions of documents that have been destroyed simply due to time. A mere look at parish records should show that ink fades and pages rot after a mere 200 years. Then there is simply the fact that a will (or any document) folded will eventually tear and that piece will be missing.
This is also the reason why probate and wills were copied into volumes separate to their originals so as to preserve the information due to the originals not being durable. PCC and all the Registers of wills recorded in every county are examples of this copying, many wills of which are no longer to be found in their original state and only exist now in probate and will registers - albeit distorted as they are transcribed over and over with errors, something a digital image wont have.
As to sustainability, I'm not sure about this one either. Whilst not only wills at this location but the UK National Archives has over 200 kilometres of shelving with over 1 kilometre of shelving being added every year. That doesn't sound very sustainable to me, not to mention the money it takes to conserve, store and secure documents, etc. Money that can be better spent in other areas.
There is no similar assurance for the digital versions, rather the reverse.
Actually digital versions are highly durable as their storage has a light footprint and can be preserved in multiple locations. It is a snapshot in time of the document in its known best condition and can be saved on multiple servers so if one is destroyed there is always many many backups.
I am sure I am not alone in wishing that in 1731 digitalisation was possible to save the Dorset Records that were destroyed due to the fire of Blandford Forum, or more recently the Irish records in 1922 of which most genealogical Irish records have been destroyed, including near all wills. Not to mention the countless documents destroyed during war, etc.
Data formats, digital storage media and the entire digital infrastructure become obsolete at pace. As I already pointed out, it is pretty certain that you won't be able to read current data in 50 years, let alone 200. The data will have to be constantly "curated" over the years, so I very much doubt that this saves money in the long run.
History is against you in this argument.
The LDS started microfilming genealogy records (parish registers etc) as early as 1939 - 84 years ago. All of those records are still accessible as microfiche, still readable, and far better off that the documents they preserved, many of which the originals are now lost or destroyed - including many wills.
In addition, such records are easily transferred to other newer mediums with very little curation required. The LDS for example have begun transferring microfilm to digital of which they expected to take 100 years to do and did it in 15 and through this process ensure that it is readable as time goes on in whatever format changes may take.
We also have the technology now to not only take a duplicate copy, but infra-red and even see details hidden by the naked eye. Preserving such documents digitally FAR out ways the negatives, including the destruction of the documents.
Sure a physical copy is nice. To see that original ink or know you are holding a piece of history that your ancestors may have held, but space is limited especially in our growing world and if a sacrifice is to be made, I'm glad they are talking about digitalisation and not simply destroying them like so many other countries do.