By this reasoning, why should any customization option in the game be locked, ever? Why aren’t all colors, accessories, card Taunts, Icons, and Backgrounds unlocked as soon as you have access to a character? Hell, why does the game even have locked Achievements?
The answer is because people like to have a sense of progression. Leveling up your profile and your characters feels good, and unlocking new customization options or Achievements is a nice reward. It allows you to show off how much you have played a particular character, because you’re using high-level accessories and their Color 10. There is absolutely nothing “lazy” or “insulting” about Mimic and Shadow skins just because they don’t perfectly match what you want them to be. I’d love more red skins (particularly a mimic-like red skin) for some of my characters, but I do like the ones we’re getting, and frankly I’m just happy we are still seeing content for KI and looking forward to whatever additional stuff is coming down the pipe.
If you want the Mimic or Shadow skins unlocked immediately, use KI Gold to buy them (which I assume you don’t want to do). If you don’t want to buy or spend KI Gold, play the game and unlock them.
If you don’t want to do either, or you don’t like the way the skins look, then rejoice, because you don’t need to spend either time or KI Gold getting them.