Thanks for sharing, fika, and man, it's something I bet just about every fan designer on this forum here has felt at some point. The most important thing is to do what's fun for you.
I tried designing an expansion years ago with a bunch of crappy, untested cards, and eventually realized that I didn't have the patience to make cards that all interact with one another, or come up with unique ideas totally unprompted (and I hardly have the time to properly playtest stuff). Instead, the one-offs (like WDC) where there's a prompt someone else gives me and I can try to solve that puzzle in my own creative way (and if it sucks, oh well, there's another prompt next week) is something that gives me energy, and I can take inspiration from all the other terrific ideas people come up with.
Card design is a process, and something we get better at with time. Go check out DXV's secret histories and the MANY outtakes (not to mention actual published cards that turned out to be duds or broken). If the maker of Dominion sometimes makes bad cards, we all certainly will too! But the key is learning why something doesn't work or is too complicated, and not being afraid to try it in a different way, or scrap an idea altogether and move on.
Any time I'm evaluating other people's cards, my main goals are: what are ways to make this card better and offer small suggestions that can help praise and retain the creator's idea/mechanic/theme while making the card simpler and more playable whenever possible. I never am annoyed by "unrefined" submissions, because honestly that's what pretty much all the cards people submit are (including mine!). The goal is to experiment, try out wacky ideas, learn from others who are tinkering in card design, and most importantly, have fun. Dominion is just a game after all!
But yeah, if there are elements of the design process that aren't fun for you anymore, don't hesitate to make a change and choose a different medium in which to create.
Finally, if you're up for it, definitely keep sharing your card ideas! We're all here for it.