The whole preservation at all costs argument rings a little hollow. You don't need to preserve everything from an era to retain enough historical data to allow for future study.
This. Just because it's old doesn't mean it has intrinsic value.
I strongly advocate for restoration of Baltimore's rowhouses over demolition and re-building, but I certainly don't think that every rowhouse needs to be preserved, nor do I think that every artistic or decorative installation ever made needs to be preserved. Many just suck, some become eyesores, and some just lose relevance; removing them and replacing them with something newer is how cities evolve and refresh themselves. If you leave every little thing in place, never to be replaced, your city will stagnate.
Obviously, you endeavor to preserve the best examples of architectural styles, and historically significant landmarks, but you don't need to preserve every hackneyed mod-style installation (which this is-the fountain itself is both unoriginal and uninteresting, and the park area is an almost text-book example of half-assed public space design) in order to avoid "losing" the history or the culture of that time.