I used to think like that, then the "Clear 100 Man Brawl As Everyone" challenge in Smash Bros. filled me with regret...
And besides, Uprising still keeps track of whether or not you've cleared a "feathered" challenge. It'll remove the feather icon obstructing the image if you do so, so you always retain the option to "clean up" your record. Already did that with the "narrowly avoid" challenges that you had to enlighten me on, so that the only feathers still in my images are the local multiplayer ones.
(that said, I *DO* want to make it a point to collect all Powers, since that also impacts the portait image in the extras)
So I'll use the feathers when I am down to my last four challenges, and if in the future I'm still crazy enough to clear them all legitimately, so be it.
I'm on a roll with the challenges today. Cleared Boss Battles on Normal, 220 kills in 9.0 in the Volcano, and 500,000 points with Dyntos. Next on my attack list is 35,000 hearts in the Chaos Vortex.
Also on DeviantArt, Rumble, DLive.tv, and the Fediverse (@freespeechextremist.com and @bae.st)