I don't know, I think it's just how you are... Some people swear, other's don't. And I think it easier to be cynical/sarcastic than to criticize in a positive way. This is especially true, if you are

a) limited in time, because you do research in your free time.

b) getting negative, or even worse, no or ignorant feedback by the other party.

c) getting tired, because you preach the same stuff over and over again.

I think is really hard to do responsible disclosure and maintain a calm attitude during the whole process. There is this awesome talk about responsible disclosure by David Kriesel who found bugs in Xerox's compression algorithms:

https://media.ccc.de/v/froscon2015-1524-lies_damned_lies_and...