All wills are publicly available, unless decreed otherwise, if they have to go through probate (proving the will), which normally applies to anyone who owns property - which, given that a lot of people own their homes, is very common - unless it's being left directly to their partner or another joint owner.
It's not something I'm very keen on, because newspapers often publish details of how much money famous people left, or even how much money wealthy private individuals from the local community left, and who it went to, which is really no-one else's business. The details of George Michael's will, for example, were all over the newspapers.
I suppose the idea is that anyone who was owed money by the deceased gets the opportunity to come forward and claim it, or, historically, that someone could come forward and say that they've got the right to drive sheep through the land or collect tolls at a turnpike gate or something.