If it is, without requesting user authorisation, then that's an illegal act under the UK Computer Misuse Act (and the USA's CFAA I think too) - modification of a computer without authorisation.

except you agreed and authorized when you installed the software. Take your position to the logical extreme - software can't make any changes without explicit, interactive approval; and you thought UAC was bad.

I look forward to joining your class-action lawsuit.

When the changes are unexpected, yes, further explicit authorisation is required. Just because you installed a photo-album app doesn't let the distributor delete all your photos, say.

Besides that, this sort of "but we hid something in the t&c-s so now we can shit on you" is the sort of thing I expect from over commercialised companies, not from what was once a paragon of the FOSS community.

FWIW class-actions don't exist in UK.