Now, I see people make that complaint, but then I see many of the same people turn around and complain about Doflamingo's name.
They "Changed" it from:
"Donquixote Doflamingo" to "Don Quixote Doflamingo"
The "change" is to take the exact same name and just add a space. This "change" is very slight and makes the name EXACTLY THE SAME as his namesake, the same complaint people make about why Blackbeard's name should be "Teach".So, why do people make this complaint? Is it just "That's not what the fansubs/scanlations did so it's wrong"? Or is there some big thing that I'm missing?
I don't think there's any "big thing that you're missing"–You pretty much just answered your question right there. In fact, you could argue that ViZ made it more accurate by adding the space.
And just for shits and giggles, I'd like to see what the reactions would be if they went even further and called him by his "original" name, Don Quijote.