Does it make sense to feel happy when an exam is easy?

After Edexcel GCSE higher maths paper 3 today I'm seeing comments like this from teachers:

"Please tell me it was a decent paper"
"I've heard good things from my students"
"My lot told me the paper was easy. I'm so relieved!"

But is a paper being "easy" really a good thing? The average student will get the same grade whether an exam is easy or hard due to the grade boundaries system. I get that increasing morale is a good thing but if students think that an easy paper is worth celebrating then equally they will become stressed when they find a paper hard. In both cases it is common for the student's final grade to be worse or better than they thought. And I would argue that a student thinking they have done well straight after an exam and finding out they haven't on results day due to high grade boundaries is the worst feeling out of these.

I think it is much better to educate students about how grades are awarded so that if they try their best then they should be content with the result and be patient until results day, however easy or hard they found the exam.

So many teachers have the attitude mentioned above so I'm wondering if there's something I'm missing?