"default other notification level when replying" is changed only in certain categories

No. The notion is that if someone replies to then they care about it, else why would they reply?

If you think that people want to reply and then never hear if people liked the reply or the conversation about their response then you would need a plugin.

I recommend that you wait until a bunch of people complain about the notificationsv(or unsubscribe from them) before you worry about this.