I appreciate you explaining your point of view an opinion in detail, a lot of posters just throw out the premise of trading Krug and that he stinks but offer very little substance as to why they think that way.
But I will still disagree with the premise. Many of the points you make about Krug are accurate, especially when he isn't playing well those flaws in his game are more apparent. But I think the positives he brings to the table far outweigh the negatives that you pointed out in his game. I am a believer that you can cover for a lot of a players flaws with simply the correct partner and some chemistry. Krug isn't so atrocious in his own end that his partner isn't able to help cover up some of his risks as he tries to make a play, and allow Krug to do more of what he does well. In my opinion, Krug played a lot better with McQuaid or Miller as his partner, as these players know each other and have been paired for most of his careers. Krug and Carlo haven't been able to develop that same chemistry and both have looked bad in some very noticeable players.
Now I am not saying the correct move is benching Carlo for McQuaid, but I don't think it's a coincidence that Krug hasn't looked quite the same moved away from Miller or McQuaid. You could also attributes some of Grizz's solid play to having a complementary partner like Miller to allow him to do what he does well. He's still been impressive, but plenty of rookies go through hills and valleys and putting him in a higher spot in the lineup doesn't guarantee he'll deliver the same results.
And my biggest gripe with the Krug detractors is they fail to address how they would replace the very important production he brings to the lineup. 45+ points from the backend and on the powerplay isn't easy production to replace, and I'm not sure any of our LHD prospects have the offensive accuman that Torey Krug brings to the table. Even Grizz, for as solid as he has looked only put up 32 points in the AHL last year so it would be a big leap to say he's ready to assume Krug's powerplay responsibility.
Krug hasn't played well in this recent stretch, either offensively or defensively so it's understandable that people would become dissatisfied with him and look for a move to add a more balanced, defensive player into the top-4. But I think none of the players mentioned as replacements (Scandella, Edler ect) would add as much to the team as a Krug when he is on his game. Add that into his strong character and leadership (yes, I think Krug is a huge part of the chemistry this team has gained) and I think trading him would have a Johnny Boychuk type effect on the locker-room.
Just my opinion though, I know many will disagree.