I mean, of course if there were lesser teams, the concentration of good players on all teams would be greater. But that is not the case in 2020, and this is irrelevant to bring that up. And as I keep exposing, while there are teams with better RWs than him, very little teams have 2 better RWs. He would not be slotted on the second line on "mid level teams" only. He would be on the vast majority of teams.
Regarding penalties - as
@Treb pointed out, he got one penalty in these playoffs. They weren't his bests due to his injury, however, and if he had been more implicated, maybe he would have been called one or two more times. But the same goes for the penalties he would have drawn. Fact of the matter, there is nothing that suggests refs are getting annoyed by his game. The number of penalties he takes per 60 minutes has been oscillating within the same range over the course of his career. He ranks 198th amongst all players with more than 500 minutes played this season in terms of penalties taken per 60 minutes.
Regarding the luck thing, what I mean is that some players end up having career years that are just not sustainable. This happens every year. Ryan Strome is a good example this past season. His shooting% is way above his career average, and his PDO is well above the sustainable 0.97-1.03 range. PDO is the sum of a player's team save% and of a player's team shooting% when he is on the ice. Even the best players in the league never consistently beat PDO over a few seasons. When you see high these kind of signals, it's easy to project a regression for one player's production.
Another thing to mention, also, is that yes, every team will have players producing more simply because they're given more ice time, even if said player wouldn't be getting the same ice time on better teams. The players who actually play more than they should generally don't outscore the opponent, and often give up on defense for more offense - sometimes because that's what the coach wants. Some of these players do progress due to being young, and end up being able to focus on a more complete game with proper coaching, understanding of the game, development, etc. Barzal and Larkin are good examples of that. Regarding Gally, as I mentionned, he produces very well despite not even getting a lot of ice time compared to other first liners in the league. And he does that while he and his line manage to shut down the opponent - and if you want to bring that up, they have faced amongst the toughest competition in the entire league. If he was not deserving of such ice time, this simply wouldn't happen.
The Kraken coming in will probably affect the cap ceiling a few years from now, since it's not out of the question that it stays put for a few seasons due to COVID. That said, of course Gally will want to get paid, especially after being underpaid for his whole prime.
Most of his playoffs games occurred before he hit his prime, which were the past 3 seasons mostly. During two of these playoffs (this season and the 16-17 ones) he was either playing injured or coming of an injury. And that's why I mentionned my concerns about his longevity. With his style, any upper body injury will have a great impact on his contribution.
I don't disagree that the best course of action would likely to have sold off the next season UFA core during this offseason to maximize future assets. Unfortunately, with Petry's signing, that is definitely not Bergy's plan.
That line hasn't been an issue. The rest has been. If they are our 2nd line, thank the gods for that because that'd mean the Habs would be cup contenders with 2 of the best lines in hockey.
Consistently being in that range is fine for first line players in today's NHL - especially when you consider he is a top 5v5 point producer. FYI, he was 36th in that regard in the whole league this past season, and 43rd over the past 3 seasons. And that's with him being stuck with linemates with generally poor finishing, which impacts his assists totals. AND that's without considering the goals he contributes for with his net presence and forecheck, where he doesn't necessarily get an assist.
Another thing is that his individual impact is greater than several players who consistently put up 10-15 more points. A key part of his game is also how, despite his lackluster size, he successfully manages to keep pressure in the offensive zone. This results in him having a good defensive impact, because he prevents the opponent from getting out of their zone. And if they do, he is alright defensively - not great by any mean, but responsible. This leads to him having a very good impact of goal differential rates - which is probably what matters the most in the end, and which points alone do not reflect.
Lastly, there's also the replaceability aspect of his production. Goals are less replaceable than primary assists, which are less repleceable than secondary assists. Most of Gally's point production comes from the first two, and he's able to drive these without having to rely much on his teammates unlike some other players who might score ~30 goals too.
As I pointed out, he is amongst the top in 5v5 production. The Habs PP has been an issue as a whole, not just for Gallagher. The strategy (get puck to Weber for boom boom) is outdated and doesn't work anymore. And I mentioned earlier it was not compatible with Gally's style because 1) hard shot from the point are unpredictable - if they miss, the zone is cleared, if it's stopped, the rebound can go anywhere and is nearly impossible to catch. For a player whose bread and butter is the front of the net, that is not ideal. I'm not implying he is a PP driver like the top offensive threats in the NHL (Draisaitl, MacKinnon, Ovechkin, etc.) who will score regardless of team PP strategy. But for many players, PP production is mostly driven by the team and coach's efforts rather than just their own - and that is why 5v5 production is more easily projected than PP production from one season to another for the vast majority of players.
Put him on a team with a competent PP that cycles the puck properly, and it's not out of the question he would have gotten 5-10 more points per season over the last few seasons.
And as pointed earlier, put him with linemates with better finishing than, say, Danault (who isn't bad at all, just not a good goalscorer), and it's even less out of question that he'd be having more points.
PS : I want to point out that what I'm saying is mostly regarding his play the last few seasons. Projecting his play going forward might be hard and it's not out of the question that he's gonna start regressing sooner than later - especially when most players start to do so at his age - forwards typically peak in their mid-20s.