My question is "so what?". Here is what you said:
Unless you're interpretting ".500" as something meaningful, why point to it at all? It'd be like you saying "The Flames will have a draft pick in the 2018 NHL Draft".
Sure, but so what? It's not about interpretation, it's about using a term that is contextually meaningless. In a league with loser points, as lightstorm points out, there is no meaning to that term, so why use it?
Well, every team starts at .500 (essentially, but don't try putting this one in your calculator). To make the playoffs, you need to end up at about 12 games above .500 at least. If at this point of the season, you're above .500, you're giving yourself a decent chance to make the playoffs, because it means over the course of your season, you've trended upwards in terms of winning percentage. There's still lots of track left, and a team that is getting more wins than regulation losses is at least on the right side of that balance, even if they need to still tip it further. Basically, the way I see it, a playoff team needs to play .500 hockey most of the season, and throw in a few good win streaks, and they'll be in. That's it. So as long as you're above .500 with a lot of season to go, you're just a couple of good streaks away from the playoffs. If you're below .500, perhaps that is true, but you actually need to reverse the trend that you've established so far as opposed to simply improving it.
In terms of the end of the season, .500 is generally a good separator between genuinely bad teams (lottery teams) and bubble teams. If a team remains above .500, they probably don't need to worry too much about their first round pick winning the lottery.
It's far more meaningful than winning percentage, because there realistically is no meaning to winning percentage in the NHL. A team can win 50% of their games and be only .500, while another can have the same winning percentage and be at .780. In addition, if there's an issue between arbitrarily suggesting there's a big difference between a team that's one game over vs. one game under .500, then that same silliness exists with suggesting that the Flames would be a better team if they'd won the shootout in San Jose and had a 50% winning percentage after all.