I'm personally pretty happy that Twitter is under new ownership, as big changes are happening, mostly for the better. As far as monetization...Welcome to social media. That's how Big Tech makes its money - with user data. Any company's ultimate goal is to generate revenue, so I don't fault Musk for trying to make Twitter more profitable. Further, given how much of the online social sphere that Twitter dominates, I am very glad that political and ideological censorship is being reevaluated. As a general rule, I am skeptical of the idea that we need any more arbitration than simply keeping the peace. Here on XDA, we don't censor opinions; sunlight is the best disinfectant, so we don't try to silence people simply for being wrong. Granted, we try to keep the conversations appropriate for the intent of this forum - focused on personal electronics, software, and development - but we aren't going to actively combat "disinformation" as that is a slippery slope, and the truth is always exposed at some point or another. I don't think it is Twitter's, or any other tech company's responsibility to tell us what is true vs what isn't; we need to encourage open, diverse discussion, where everyone has the right to express their opinion even if they're wrong. If certain beliefs and opinions are actively suppressed, or certain information is intentionally withheld, it's not truly a free and open discussion.
But, a lot of this also comes from my personal belief that freedom and democracy go hand in hand; unless EVERYONE has an equal voice and equal liberty to believe and express what they want, it's not really fair, is it? So, that would be my primary concern for a platform like Mastodon: Is it truly neutral? Does it have a social, political, or ideological agenda? Does it actually promote freedom of opinions on their platform? Does it censor information, particularly when it comes to the press? I think the open source and decentralized nature of Mastodon is a good way to guarantee this.
That's just the "ethics and ideology" take.
As far as technology and quality...A big part of why decentralized services such as IRC lost popularity is because of their decentralization. What the Big Tech services excel at is user oriented features. Big companies are always going to have more resources to produce a better product. Mastodon on the other hand struggles with many of the same issues IRC did - where there are a lot of competing clients/softwares that provide similar services, all with different feature sets.
If someone were to come up with something that works similar to Reddit, where each sub is controlled more or less independently by its own moderators, but where the user experience is similar regardless of where you are on the platform...That would probably have a better chance of catching on. The big problem with Reddit is that the entire site is hosted in one place, and the admins/main moderators of the site often exhibit significant bias.