There have been a few discussions about this here actually, I can certainly see how it would be a powerful tool! There are a couple of concerns though.
On the reading side, right now we upload textures to the GPU memory and then release them from main memory, so we would need some way to keep a copy in main mem that could be accessed by Blueprints. Means knowing the textures in advance (or copying back from GPU mem), and could use a fair bit of RAM.
On the creating texture side, the thinking right now is it would need to be limited to editor-only. Blueprints are just not really fast enough to process large 2D arrays of data at runtime. You’d also need to compress and store that ‘source data’ so it could be converted to platform-specific formats during cook.
We’ll certainly keep it on our radar!