I disagree. I think you can acknowledge the achievements. But celebration flies in the face of the "cost" that it took to achieve.
I guess what I'm saying is we'd need a time machine and go ask some people that were killed if their involuntary sacrifice is worth celebrating. Their answer may be different than ours.
Not being entirely specific to this instance but you could say that about so many things, nearly everything in fact. Its pretty damn rare for anything of note to not have a cost and 'sacrifice' attached to it. Even sporting events, something like a world cup ends up killing people to achieve. People only tend to mention it when it starts entering into 'village' levels of death, as if several individuals dying is okay. Difference being there are no memorials commemorated the world over to remember their sacrifice. Same with scientific discoveries. Some even get a free pass with many, deeply religious people will point fingers at such a death toll from an empire while ignoring the body count of their own religion (or even from the book itself).
And I am sure the answer from most people who died from anything, be it noble or by choice, may want a different outcome. If you took a soldier from WW2 who was going to die and bring him to the modern world, ask him if its worth it and if so he gets sent back... yeah.
And lets be honest, the divisions
left over by the British in many areas were there beforehand and will be for a long time after. Finding new and creative ways to divide ourselves from each other is the number 1 past time in history.
Anyway, for the question I think it is a case by case basis as every country is different. That is pretty complex to work out on their own whether it was worth it, let alone overall. Hard to find many countries without anything shameful in their past, can't gloss over it but I think people are too obsessed with this 'perfect' ideal of a country or person and what you can find pride in. When you look at anything with a microscope, things get pretty ugly. Idols and heroes suddenly become villains and despots. I grew up being told how amazing Churchill was in school, they left out a lot of the bad bits which I found out on my own behalf. Took the shine off him, as it should, and realized he is deeply flawed as are most people (I'd say all, but must be exceptions). So in summary, everyone is a bastard, but the scale of what kind of bastard you are can vary greatly.