There's generally nothing wrong with simple wallpapers. It's the line between too simple and simple on the eyes.
There's nothing wrong with this wallpaper either... but I wouldn't be surprised if it was criticised for slapping a scan onto a paint bucketed canvas, some text and two perpendicular lines with a square. It could very well be something people might consider low effort- despite you fixing up the scan.
Some abstract shapes or some sort of brushwork in the background would have been ideal and made it promising so that it wouldn't be deleted.