I usually avoid these types of discussions, but here goes. Your points are well made.
At the conclusion of the Civil War, within five years, Union statues and memorials were erected on battlefields, most of which were in the South. The South was defeated and basically destitute (economy wrecked), and could not afford the cost to build any. Did you know that 20% of Mississippi's 1866 budget went for prosthetics? Most of the Confederate memorials that are in question were built 15-20 years after the War, and those on the battlefields are dwarfed in size by those built by the winning side. And yes, I'm sure some were build explicitly to remind the freed slaves that they were still under master's control. But some were built to remember or memorialize family members that perished in the War. Looking at Union statues on Southern soil after losing the War had to be hard to stomach for some.
Anyway, end of what little I know. I only hope that we don't always use 21st Century logic to explain and do away with 19th Century actions. We might decide that some of our heroes (Washington, Jefferson, etc.) also don't deserve the memorials we've built.