Stopping change might cause conflict and war, but randomly drawing lines on a map and calling the result a country has caused an awful lot more in recent memory. :P
The big problem is that most areas have people with vastly different opinions about where the lines should be placed. Even relatively peaceful neighbours such as Greenland/Denmark and Canada. So no matter where they end up, someone will disagree. But yes, you are right: Belgium was a mistake.
:P
Most of Africa was more of a mistake.
The African borders were deliberately set by gready bastards, and have caused only misery. Belgium, with their 5+ levels of bureaucracy and pissing statues, have at least some entertainment value.
I can agree that having different countries has value, since you can test different types of government, and adopt to the geographical differences. But the borders as they are today only have value if the inhabitants agree, and if they contribute to keeping the conflict level low.
To;dr: we would like the Faroes and Shetland back now, please. And we need to discuss the lack of payment for Isle of Man, Orkney, and the Hebridies before brexit goes through.