"Everything in moderation."Also, Latins said "repetita iuvant".
There is a point at which repeating the same opinions/critiques/whatever becomes ineffective and even counterproductive.
Too much repetition is not good because it adds nothing new, and never adding anything new leads to nothing ever progressing. In the case of forums it means circular discussions that are just that, circular and never go anywhere except round and round along the exact same tracks. I personally see zero point in that.
(Yes, the same would go for constantly praising the exact same things. That just never happens here.)
In a sense it would be good to get fresh news to digest and discuss, however... I have some doubts.
Ultimately, CDPR are professionals, and therefore what they do or don't show is bound to be a decision with solid reasons behind it -- although (or "even if") said reasons are never revealed. That's part of the reason why I won't care if neither E3 nor Gamescom brings new material; it's not like they owe the community a third demo or anything of the sort. Because they don't.