Teams rich in tradition don't stray far from their classic look. Let's examine further...
The premiere teams in this league historically(SB wins and playoff appearances):
Pittsburgh Steelers- uniform has undergone virtually no changes. Numbering has changed, and they reintroduced that ugly throwback.
Dallas Cowboys: There have been minor variations to the same theme throughout the teams history
San Fran 49ers: They switched it up a bit in the late 90s as we did, but they're back to their classic look.
Washington Redskins: From their inception, they have had many different looks. From a burgundy helmet with a feather up the back, to the brief Lombardi era yellow helmet, to the arrow, to their current look. Their current look is their historic look, however, which they won all 3 of their rings in.
Green Bay Packers: Obvious. No changes. Never will be.
Colts, Bears, Saints, Eagles, Browns: Not many accolades to their names, save the Colts and Saints of late, but all of these teams uni changes have been minimum
Dolphins: yes, we updated in the late 90s to a more modern look. Could we rock a striping scheme similar to the Broncos, Panthers, Chargers, or Vikings? Sure. But a uni re-design costs $$$$.
Teams that have undergone major uni changes:
Seattle Seahawks: Their logo was modernized, and their colors completely changed from grass green, royal blue, and silver, to neon green, "storm" blue, and navy. They had no rich history in their old unis though.
Tampa Bay: Obvious. One of worst franchises in history until they went from Creamsicle to pewter and red.
Vikings: Not that big of change really. Modernized their striping, colors remain the same
Lions: haha. how many different uniforms in the last decade? 3? and we all know their story.
Falcons: modernized logo, colors remain the same.
Broncos: perplexing a bit, but Elway never won in the orange crush. He won two in their current uni, which probably won't change
Bills: went to navy. can't blame them. How many SBs did they lose?
Cardinals: same colors, new uni. New results
If the Dolphins change their uni, they should eliminate dark blue (an overused color in the NFL- 8 teams), but I think simplicity is best. Straight lines are more intimidating than curved lines.