You know what is kinda dismissive though? Claiming that Lost World was 'universally hated'. But someone simply saying, 'I, personally, didn't like Sonic X' or even 'I think the majority of people disliked Marine the Racoon' are absolutely not dismissive at all.
If someone were to say something like, 'Oh yeah? Well, you liked Sonic Adventure, so you're not allowed to talk!' that would be dismissive. People expressing their opinions does not mean that they are dismissing other people's opinions, it just means that they differ. If you're worried about the discussion becoming too dismissive, then I feel like you're going about this the wrong way. The whole conversation surrounding Sonc Forces needs to move on from an initial gut-reaction at the sight of classic Sonic. I'd be a shame for 'classic Sonic' to become another one of these negative phrases.
Evne the phrase 'Sonic Adventure' has been used this way in the recent past. What I'm saying is that the Sonic fanbase sometimes has a problem of using certain negative phrases as a way to shut down discussion.