IMO that field is important for testing bugs in the correct or at least a close wine version in order to reproduce the issue.
But it should be equally useful for this as long as it's a version where the bug is present. It doesn't matter whether it was the originally reported version. I've not seen any explanation in this thread of when any affected version is not good enough, and you really need to know the version the reporter was using. I believe there is no situation where that is important, and people changing it back are just adding noise to the bug for no good reason.
In fact, I would like to propose that we change the field's definition to be the LATEST WINE VERSION in which the bug is known to be present. This way, people retesting bugs won't have to flood them with comments of "still present in version x.y.x", and one can quickly search to find e.g. download bugs that weren't tested recently.