Because what Photoshop needs is more features.
Adobe also sees Photoshop as an ideal intermediary step between designing 3D models and printing them. The tool can take virtually any 3D model in the standard OBJ, STL, 3DS, Collada and KMZ formats and prepare them for printing. This means adding the necessary scaffolding and rafts so the models can actually be printed, for example. It will also look for potential issues with the model, so users don’t waste a lot of time and material trying to print a model that doesn’t actually work.