I've been thinking a bit over the last few days about the idea of preserving historical monuments, and I think it's complicated.
That's an understatement! The whole matter has so much ideological baggage that, when you get the behemoth of commodification sitting on top of it, it gets to be a real mess.
I've been to Stirling Castle, and you're right: when a location becomes a tourist destination, we do whatever we can to downplay issues of authenticity and politics in favor of making it an inoffensive, family-friendly spectacle. The castles and manors of Europe, therefore, aren't ostensibly monuments to Eurocentrism, colonial plunder, or hereditary succession, but we realize that that's what they represent. I think the Louisville monument is more problematic because it's not exactly a tourist attraction, and its ideological meaning is a lot harder to obscure since we're still fighting the Civil War. The discussion has already touched on the long and ignoble legacy of Northern triumphalism that periodically scourges the Southern States; cynics like me say it probably stalled the Civil Rights movement for decades, and now it's desperately trying to simulate progress for a minority that deserves more than cosmetic change.
My wife's family came from Hungary, where they still have statues of Attila the Hun. But they're also used to having successive waves of political overlords alter their civic landscape to one degree or another to fit the prevailing ideology. Whether you think it's a good thing or a bad thing depends on our vantage point, and what lens we're using to see the tourist attraction.