Another benefit of layers is the ability to combine different images to form a composite. While I can see that a full blown layers system in Lightroom would start to blur the gap between the two apps, I would welcome the option to overlay a second image, such as a texture. It's something that could be done in the darkroom and I'm sure it could be achieved in such a way that it was quite distinct from Photoshop's layers implementation.
The Spot Removal Brush is a very useful and powerful tool for removing spots from your photos and in Lightroom 5 it has been given a boost with the ability to be used to paint brush strokes with the integration of the Advanced Healing Brush. If you've seen Adobe's video showcasing how this works, you'll appreciate how it can be used rather like the Clone Stamp in Photoshop. However, in practice I found its effectiveness depended on the subject it was being applied to as you do need a suitable donor area. On more than one occasion I found myself pining for the Clone Stamp which does make the updated Advanced Healing Brush look a little hamfisted.