And the most salient fact about all of those is that they were hardly even revolutions. The Soviet Union stopped supporting its puppet governments in those countries, and the people of those countries, who had been more than ready to quit Soviet rule for quite some time, just did it. No fighting was necessary because practically nobody in those countries wanted Soviet rule anyway. This has been true for few if any other revolutions in history.
If we get to simply exclude all of the successful and largely bloodless ones, then of course revolutions are messy and risky. It is that way by definition!
The term "revolution", while it does not have to imply bloodshed, does imply some kind of struggle involved. My point about what happened in the countries of Eastern Europe when the Soviet Union fell was that there was no struggle at all, not even a bloodless one. Everyone just said "about time" and went about the business of running their own countries.
This is absolutely a case of survivorship bias.
In other words, if the actual facts had been different, we would use a different word to describe what happened. Yes, indeed. That's why we have different words: to capture meaningful differences in the facts we are using the words to describe. If we simply called every change in government a "revolution", the word would be useless.
I think that's rarely the case, at least not when the people starting the revolution are reasonably sane (by which I mean they have a reasonably good grasp of reality and use that to guide their actions). I think the people in Eastern Europe who started "revolutions" when the Soviet Union fell had a pretty good idea that little or no bloodshed would be required.
It's quite possible that the people who started the French Revolution didn't realize how much blood would be shed, but to me that just means those people were not reasonably sane. And there is plenty of other evidence that they were disconnected from reality.
(By contrast, I think the people who started the Russian Revolution, and the Communist revolution in China, were well aware that much bloodshed would be required, and they were perfectly OK with that. That makes them reasonably sane by my definition, but it does make them "insane" by other definitions--psychopathic or sociopathic, for example.)
For one thing, when it's won, the losers go back home. After a revolution, they stay around. Which is you often end up killing them.
It should be noted that often when wars of independence happen there are still many people who identify with the side of the "losers" whose homes are on the "winners" side, and vice versa.
For example Greek independence did not magically transmit the Turks living in their borders to Turkey, nor did it transfer the Greeks living in Turkey to Greece. What was needed to resolve that situation was ethnic cleansing via the deportation of the populations to their respective countries, in such that a country where they hadn't lived before can be called "theirs".
'Most' revolutions of the modern age were anti-colonial revolutions, in places like India and Africa, in the aftermath of WWII.
Life under colonial rule in those places was, as a rule of thumb, not great.
We then had a large string of revolutions in Eastern Europe, in the late 80s/early 90s[1]. Would you also describe those as a 'worse outcome for the citizenry'?
[1] Which could also be described, if not as de-colonization, as an end to Soviet imperialism.