I commend them for trying to improve. They've done well in that regard. Now they've got key pieces in place; all that's left to do is work hard, try to stay healthy, work towards good chemistry, and let the chips fall where they may. Many very good teams in every sport have been unable to "get over the hump" and win a championship, despite all their efforts to do just that. All you can do is put together a good team and hope it works out. Sometimes it does, sometimes it doesn't.
What you're seeing from fans is probably jealousy. If their team doesn't do well in the offseason and they see another team doing REALLY well, they get a little irked/jealous. "Why isn't my team doing that?!" Or for smaller market teams (mainly baseball/basketball), "I wish my team could spend that kind of money to get a really good team!"
I'm sort of a hypocrite in that, being from L.A., I'm a Laker fan and I love it when they beef up their team with the likes of Pau Gasol, Ron Artest, etc. But, when I see the N.Y. Yankees or the Miami Heat do it, I get pissed. It's just my "fan bias".
That's exactly what it is. If Dallas or NYGiants was the team making these moves, I'd be super pissed.
“Everybody has a secret world inside of them. All of the people of the world, I mean everybody. No matter how dull and boring they are on the outside, inside
them they've all got unimaginable, magnificent, wonderful, stupid, amazing worlds. Not just one world. Hundreds of them. Thousands maybe.” -Neil Gaiman