I think this is a tricky issue. I do believe that the communication by Paradox devs on this sub-forum is not as good as that on the forums of other games (such as EU IV or CK2). At the same time, Stellaris fans seem more unhappy with their game than fans of other Paradox games - I am not sure there is much "toxicity" per se, but I can see why devs would be unwilling to interact. In general, the relationship between developers and fans has been somewhat complicated basically from the start - for instance, I do not think that other forums ever had entire topics of discussion fully "quarantined" in their own pinned thread, such as for performance now or for sectors in the "good old days".
I think that one possible cause for this is that, for whatever reason, there seems to be a large discrepancy between how the game is viewed by who is active on this forum and by customers at large. While the majority (or at least a large number) of forum users seem to agree that the game is marred by serious problems, which have been left unaddressed for too long, Stellaris seems to be selling very well: it was in the "silver" tier of
steam top sellers for 2019, which is very good for a 2016 game (also, it was one tier higher than CK2, HOI4 and EUIV!), and it seems that Federations sold extremely well too (see
here, for instance). Further, there does not seem to be any serious decrease in player numbers (they are quite stable across the last 4 years - see
here). And whenever Stellaris is mentioned on the main gaming websites the tone is generally extremely positive - I have never read an article on Rockpapershotgun, Polygon or other outlets in which performance and bugs were even mentioned as possible issues.
Thus, I think a possible reason for the "uneasy" atmosphere on the forum is that, while most users think that the game urgently needs extra work on bug-fixing, performance improvement and balancing, the devs look at sales numbers and general reception and conclude that most of their customers are actually quite satisfied. Maybe the devs do not say much because they don't have anything to say which would make the forum users happy - they are not working on some massive rebalancing and patching of the game, they think that the current issues and bugs are not THAT big of a deal, and think that the opinions on the forum are not representative of what most most players believe. This makes the forum users more annoyed, which in turn reduces the willingness of devs to interact with them.
To clarify, I think the game has serious issues - I play on 2.1, have not bought Megacorp nor any later DLCs, and think that the massive overhaul of 2.2 was a sub-optimal use of resources, which might have been better employed to build on the 2.1 framework. That being said, the game seems to be doing great, so I guess I am in the minority. It's possible most players do not really care about having a competitive AI, play only up to the mid-game (so they never encounter issues with broken endgame crises and performance), and do not worry about resettling pops (the AI is not gonna punish you for playing sub-optimally after all).