That the statue was still created as a corporate advertisement, regardless of whether the plaque is present.

A lot of great art was originally sponsored/commissioned by wealthy corporate benefactors (for example the Catholic Church and nobility in 15th century Italy).

I think it's important that the beholder/public in general is aware of the providence of a piece of art, yet I doubt banning corporate sponsorship of art would be a net positive for society.

It certainly wouldn't be, though in this particular case it could be argued that corporate sponsorship renders the work tasteless.