A armored vehicle, by its very nature, has limited uses, it is a big vehicle designed to support operations outside. Officer safety is vitally important, but this should not be used as a excuse to justify the violation of citizen rights, to justify violations of the law. Securing a quick resolution to criminal activities while protecting officers, where their use is appropriate, does provide a incidental public benefit, but armored vehicles do not keep the public safe.
The mere presence of a armored vehicle is not a violation of any citizen's rights, or the law. The monetary cost aside (maintenance), I have no issue with LEAs having these vehicles. In fact it is unlikely I will ever see one of these up close and in person.
As to the "used to oppress the public is bogus", your view is just as valid as the opposing view, it comes down to how the equipment is used vs. when it is used. Like a firearm, it is a tool that is, hopefully, used within the confines of the law.