I made this exact argument in a HS English class, in which we held a class-wide debate about heaven after reading some book about it.
Unfortunately I live in southern Missouri, so the "debate" groups were basically group 1: 12~ super religious Christian kids vs. me (we had to announce our beliefs beforehand), group 2: 12~ super Christian kids vs. the only other person willing to do anything other than agree with one another.
The debate sucked ass, but I pretty much made the precise argument that the idea of a heaven where you're literally always worshipping and happy sounds legitimately awful, and that an eternity of that would wear down on literally anyone after a while. The counterpoint was that you're incapable of feeling anything but happiness in this idea of heaven. My argument for that was that it sounds like you're not even really yourself at that point, but more of just a blindly faithful zombie more than anything if you can't even think for yourself.
But yeah, evidently the idea is that you're always happy and can't feel anything else, apparently.
....Bit of a tangent, but man my high school was a hellhole. I lost some friends for even daring to engage in that debate (if I didn't, it would have just been a circlejerk about how awesome God is I guess, which is apparently what people wanted). My social studies class was taught by an ultra religious lady (who is probably dead by now cause she was super old) who used to do study games where people competed for points, with the winner winning Bible verses.
Also, we had to do debates in my Physics class one time, and I was literally the only person in class who was willing to argue in favor of evolution. I argued that evolution was well-proven and easily identified on a smaller scale, and thus that smaller changes over time can demonstrate larger-scale evolution. Instead of the other kid responding, I got to debate the teacher (who is super, super, super religious, moreso than most there, and who was also old so is also prolly dead now, so get wrecked bitch) the entire time, and she repeatedly spoke over me and talked down to me any time I tried to argue my points. I got a D- for it and the other kid got an A despite saying maybe two sentences the entire time with the teacher doing almost all of the arguing. Even the other kids agreed that it was bullshit.
Kind of a rant, but going to HS in the Bible Belt as an agnostic sucked ass. I guess I should have just stayed quiet.
geez, it's like living in the God's Not Dead movies