Maybe we could compare island building to creating art. There are lots of people incredibly skilled at drawing stuff. There are also lots of people who "can't even draw a stickman/circle/other basic thing." But really a lot of it isn't talent, as we tend to believe - it's application of techniques and imitating what you see around you. You learn to draw a cat after you've stared at lots and lots of cats and painstakingly practiced getting their details right. You learn to shade, draw wrinkles on clothing, etc, by doing similar. I notice a lot of these good islands make use of good design choices like how to create open spaces without them feeling empty, how to arrange/mix/spread out flowers and make natural flowing paths, how to create cohesive natural-looking multi-level neighborhoods, how to make use of things like weeds, objects, patterns to decorate in unique ways, etc.
You can't create in a vacuum - whenever we use our imagination to create something it has to come from ourselves or our experiences or what we've seen. Want to create more beautiful things? Immerse yourself in more content and dedicate your efforts to replicating it on the canvas - in this case your island.