All other rolls, (outside of combat), are easy to adjust to taste. After all, the GM determines if a roll is Easy, Hard or Daunting.
At my table, we like that skilled characters succeed on most average checks, that's why they are trained, to pull off that kind of roll.
Each to his own of course. But I wonder if adding a purple to all checks doesn't make Chaos stars a bit too common. I prefer to add misfortune to up the ante, because misfortune are linked to story elements. To add misfortune to a scene, you need to add narrative challenge, descriptions of challenging circumstances. That, IMO, really adds to the story.
i.e.: If I want to make a situation harder, I add elements that hinder the PCs actions. That could be gale force wind, heavy rain, deep mud, an extremely fatiguing ordeal just before the scene at hand, faulty equipment, misinformation for social checks, etc…
By doing this, I send a clear signal that circumstances are perilous and PCs should be cautious and well prepared or supported to make their checks. And it adds flavour, mood. It makes for memorable scenes and fires up the player's imaginations.
Lastly, it makes good conditions seem a blessing. PCs really appreciate rolls without misfortune after having gone through hell. It creates a nice mechanical contrast between climax scenes and day to day activities. Which, in my view, is compelling story-wise and also feels realistic at the same time.