Except (as far as I know) no one is suggesting erecting monuments to Confederate soldiers now. We're talking about established history.
People are putting up monuments to slavery now. Richmond, VA has Monument Ave, filled with Confederate monuments that are never going to fit in a museum (it also has a really bad statue of Arthur Ashe looking like he's gonna' beat some children, but still, it's a black guy memorialized at the end of a line of Confederates.) It also has erected a monument that recognizes that under a bustling interstate a lot of folks were sold off, died and buried in nameless graves. You can recontextualize history without having to move anything.
The fundamental disconnect we're having here is that people are essentially arguing the monuments as they stand now are the cause of continued racial animosity. An old statue thousands of black people in cities everywhere across the country pass by on their way to work or home isn't traveling through time to oppress them. It's people living now doing that. The past can't hurt us unless we forget it and pretend we're evolved past it, and the iconoclasm proposed by people in this thread feels like that's what they want. There's not any inherent tension between wanting these statues to remain and recognizing that racism hasn't gone away and that, forget the dead, we have people alive today who are suffering in ways large and small.
(As for your final comments on "glorifying the oppressed", that sounds like historical revisionism as well, just of a different stripe than lost cause conspiracies. But then we get into a deeper philosophical question of memorials and their innate distortion of history.)
Landrieu's argument is eloquent, and I see its merit. LA and cities ultimately can decide their own course. I just disagree with his argument.
This feels like you acknowledge the issue but don't give it much weight. The confederacy is forever tainted by its ties to slavery and everything that goes with it. The KKK wasn't choosing to have gigantic Klan rallies at Stone Mountain Georgia because of the beautiful natural scenery. Much the same the confederate flag wasn't being waved around during all those cross burnings and constantly used by white power movements because they're all so well aware of the horrors of slavery and racial oppression in America.
You can't just untangle these statues from the last hundred and fifty years of ugly racial oppression in this country. They're one in the same for the lowest of the low in American culture and when they look up to those statues they're not seeing the millions of black men and women who were beaten, had families broken up and were treated like a piece of property. No they're seeing the idealized versions of racial injustice quite literally on a pedestal.
These men no longer just stand for the confederacy, which is horrible in of itself, but for all the ugly racial sentiment in America to this day. To say otherwise ignores all those lynchings made in their name and the other horrible acts performed in the name of a bunch of traitorous losers.