I'm in favor of restoring the notifications at a minimum, for most or all of the reasons mentioned above.
As far as it affecting the opinions of posters or the willingness to express unpopular opinions, I think it can do both, for sure. But it's also a mechanism to communicate shared values and beliefs.
Humans rely on a lot of complex social cues and testing "in real life" to create communities that are obviously not possible online so I don't think it's unreasonable to use reaction stickers as a proxy for that. For example, I determined fairly quickly that I am not an "A & H" person for the most part based on how different posts are received.
This isn't unique to this site. Years ago I noticed an increasing shift in the Reddit userbase and determined I was out of sync with them and stopped using the site. That's a good thing, in my opinion. I don't think anyone would argue that I should have spent my time trying to adapt my thinking to fit in there.
Finally, I think reaction scores should be visible again. It's a useful metric for me when encountering outlier opinions, dramatic accusations, or challenging perspectives. There are several threads which by their nature tend to have gay-oppy aspects where people are pushing agendas for reasons not clear in their posts. The reaction score can be a proxy variable for the reliability of a user and it's helpful when parsing a lot of new information and deciding how much weight to give to a particular piece of information.