I really don't see anything wrong with fans holding that perspective. What you view as the priority and goal for the team is going to have far more of an effect on your own enjoyment of the team and its season than it will on the success or operations of the team.
I also see the goal of making the playoffs being one that is far more in the control of an organization when it comes to roster building and transactions than "making a Cup run." The playoffs are often a crapshoot and can be a very fickle beast. Who would have predicted Chicago, with all that talent in place, getting bounced in the first round last year? In retrospect, we were probably the worst matchup for them when considering our speed, defense and ability to attack in transition...not to mention the X factor of a hot goalie. If they draw St. Louis, Minnesota or even Anaheim in the first round instead, do they wind up in another Cup final? If we draw a bruising Anaheim or St. Louis team in the first round, and still manage to win the series, do we have enough in the tank to get through the second and third round?
That said, the more talent you can put in place, the better chance you'll have to make the post-season AND do well in it. But it's far from a sure thing. And overpaying in assets that can keep you competitive long-term for a talent injection coming off the worst season of his career carries no guarantee of a repeat post-season performance.
I love your last line though. Let's definitely keep it in perspective. Hope for the best, reasonable expectations, and another set of thrills when this team passes them again.