Sorry, but this is wrong. Review history has been set up such that 6/10 is bad. 5/10 and below are generally reserved for unplayable.
You can say it shouldn't be true that 6/10 is bad (and I'd agree), but you can't just arbitrarily change things for one game, where 6/10 represents a bad game on 99% of games but not this one.
Well, it's about time professional reviews start to use the scale properly, imo. And I think this trend (?) actually started at the start of the gen (or even slightly earlier), not with Destiny.
I don't see any issues with Destiny's review scores whatsoever. The game really isn't THAT good, the issues are clear. Also, the average Metacritic score is 75, not 65 or something like that. What I'm saying is that 60/100 would be pretty bad, sure, but the score is actually as high as 75. 6/10 shouldn't be 60/100, imo, but it "averages" around 75, so it's ok. And so is the game, imo. It's just ok.
And I really doubt "casuals" are going to keep playing this for long, but we'll see.