That doesn't make them history or historical documents. They're a token, they offer no information besides "This is a thing that [probably, some monuments aren't about real events or are about faked events] happened," and "the people in this area support and approve whatever this monument is commemorating." Historical documentation of events and people, besides the documentation of the monument itself, is not damaged or helped by the removal or addition of the monument.
You can have plaques and information kiosks and such to go WITH the monument, but a) that is not necessarily connected to the monument itself, you can have the plaque without the monument, and vice versa, and b) in this specific instance, as far as I'm aware, there was no such informative plaque.
And you can have it be akin to a historical document, sure! But that's not intrinsic to it being a monument; Thousand year old statues with no surrounding documentation, "best we got" tier documentation.
In this instance: It's not thousands of years old with no surrounding documentation, like the monuments ISIS blows up. It's not supported by the population it dwells within. And it offers no new insight into the time or place it was put up or what it was commemorating. It *only* serves as a symbol for the population and the place, and the population does not want it. Why keep it up?