I think this is a very good idea! Honestly such a pain to constantly walk in and out of boss rooms. Even once you get high-leveled and fight bosses like will, gloom, and onwards, you're … (more)still doing a lot at once. Or at least I do. As soon as it hits reset I'm going down the list like a tax collector after money and satisfaction haha.
This is beneficial to lower levels too, though. They benefit from early bosses so much more and will be doing all of them quite often. Even if it's a small QOL change, I think it's still an important one- like the kind of difference made when nexon let you open all your skill nodes at once. It just flows so much better. (less)
