XH558 was a totally worthwhile project and a credit to those who kept her flying for so long. It also allowed countless people of the younger generation to experience the awesomeness of seeing a Vulcan flying. Maybe even inspired a few to get into aviation. So let's not get into some kind of retrospective imagined scorn-fest. i don't recall anyone saying it was unnecessary at the time - certainly after its final "maiden flight". What I do recall is folks by the thousand flocking to see XH558 at numerous shows and flypasts. Even more for the farewell tour.
But what we shouldn't forget is the widely-held view at that time, that retiring '558 to Doncaster would not be a good idea. Also that its proposed use as a training tool was tenuous at best; naive at worst. Sadly that has proven to be entirely justified.
And there may be 'plenty' of preserved Vulcans out there (actually 18 I think), but few have been hangared in recent years as '558 has/had been. Therefore its overall condition alone justifies it being placed somewhere safe, and under cover (but pointless if not).
So I think we need to consider XH558 as the unfortunate victim of selfish motives rather than an object to be derided. Then hope that a responsible and realistic custodian can be found.