While users on social media platforms are frequently resistant to major changes in the way they communicate, there are actually some good reasons to be frustrated by the change and pleased to hear Twitter is listening. If everyone can see replies it clogs the timeline and can also expose people attempting to have serious conversations about, say, politics, to trolls. At best, that makes it less enticing to engage. At the other end of the spectrum, it has the potential to increase exposure to harassment for some users.
Many have complained about Twitter needing to do something about harassment issues on the platform — and they have taken some steps — but exposing replies to everyone's main timeline may actually be a step in the opposite direction, as many noted Thursday night.