Sounds more like your system is garbage, as much as i dislike RetroArch i can't say that ever happen to me. Also if it pisses you off that this is the only emulation for Wii U, then why don't you make one?
Retroarch never gave any trouble to me, but I have a solution for you, I've made a pack with all GX emulators with GamePad support (NES, SNES, GBA, Mega Drive, SEGA CD,...), you can give it a look. If you know how to place Wii apps on SDCard and install things with WUPInstaller you will have no problem with it.
It's not garbage, you're just being ungrateful. Nobody has to do any work specifically tailored for you and it's nobody's fault you're having issues. The very fact Retroarch exists is the reason many systems are able to be emulated right now. Start looking outside of your bubble instead of complaining about stuff other people do out of their own free will.
Try formatting your SD card, redownloading another version, reading a different tutorial, trying out a different version (.rpx instead of whatever), using a different SD card, using a different core, or just play an emulator in your PC. Also try to be a little more grateful for other people's work instead of just whining about it or else you'll probably gonna suffer a lot later in life.