A few years ago -- and, continuing into today -- there were numerous security concerns around EXIF data. This included not just GPS data and personal security (and/or privacy), but also other identifiers including device serial number (and manufacturer/model) and the ability to cross-reference same between pictures, picture sources, and potentially purchase history. (Depending where and how you purchased, the serial number may be correlated with your credit card or other payment account.)

Now, for the latter: If you are publishing controversial photography, the last thing you may want is to have said photos traced back to your identity. For the sake of this argument, I'm going to assume you are one of the forces for good. Omniscient data sourcing is not always desirable.

In this specific UK case, and with a rather light and superficial reading of some news accounts combined with past reporting and experience, what I see are organizations who have been called out both publicly (bad publicity) and financially for blatantly copying and publishing photographs for which they made no effort to acquire rights. (There is an existing system for this, which they simply ignored and refused to respect until dragged into court -- formal, and that of public opinion.)

I speculate that these entities know that many major distribution platforms now strip metadata. And, that they are working to take advantage of this through the current legislation and sought definition of "orphan works".

I think those distribution platforms themselves may also be complicit. We've seen how Facebook has repeatedly attempted to use its users' photographs wholesale and without individual notification/approval for its own gain. (E.g. The "we can and will use your photographs in advertising" controversy, amended after much vocal blowback to include a (difficult to find) opt-out setting.)

Personally, I think that the pragmatic route people may find themselves taking in the face of such legislation passing is to watermark with copyright notification anything and everything they may care about, before uploading it to any public source. If it is subsequently reused and this is of sufficient concern, the original upload including date/time can be cited in demonstrating that subsequent, ungranted reuse that is missing said notification must result from deliberate (and illegal) editing to remove said notification.

This will be ugly and doesn't fix anonymity issue, but so be it. (And deliberately publishing without copyright information has always weakened the stand of a creator subsequently defending copyright. In many of these cases, public communication of the photographic content (or other imagery) may continue to be more important to the creator than maintenance of copyright privileges.)

TL;DR: Meta-data (EXIF, et al.) used to be more commonly retained. This causes numerous issues particularly around security and privacy. Stripping it became de facto policy amongst many major distribution platforms.

Numerous, influential agencies seek to make a buck any way they can and to leverage or compete with near real-time peer-to-peer sharing and "news". Also to leverage and/or compete with peer-to-peer interests (i.e. inject noteworthy advertising). They see an avenue to using these materials without legal and financial repercussions.