As a Roblox developer, it is currently annoying to put together simple UI using anything but rectangles and squares.
To remedy this, I suggest that, inside the Versions/version_here/Content folder or somewhere similar, a set of basic geometric shapes, such as triangles and circles, in black and white variations be made available in a new, convenient folder. This would enable less asset uploads (and maybe even faster load times?) for basic flat UIs that are somewhat common in modern Roblox games and in the process improve developer convenience at the minimal cost of adding a few images, or even a spritesheet, to the next build of Studio and the player.
This would also enable studio-only UI creation to be simple and viable similarly to studio-only asset creation, which I feel is in spirit with Roblox’s goals for Studio considering the build contest and previous updates which have made it both easier to integrate powerful external tools but also made the existing internal tools more powerful in the process.
If Roblox is able to address this issue, it would improve my development experience because I currently rely heavily on the Content folders to keep my game UI aesthetically consistent with the default Roblox control design and avoid tangling with moderation unless absolutely necessary.