But shouldn't it still be a rational decision?

The imho rational thing to do, would be to compare the pros and cons of each option and find a conclusion that way.

Comparing only the pros of one solution with only the cons of the other, seems a bit... disingenuous and an emotionally-driven line of argument.

And I personally just do not believe that making decisions with such wide-reaching implications as monolith or microservice based on emotional arguments, does lead to useful results?

The only thing that imho can come from this sort of arguing, is the kind of religious divide, evangelism and proselytism that ultimately only hurts both sides of the argument, because it makes people favor dogmatic choices over considering what's actually useful in the current situation?