This is on the official suggestions list There are some issues with adding an erase function, so no promises, but we will be looking into it.

The eraser does actually respond to paint depth/texture, but only slightly at the low pressure range (as it's designed more to remove paint than edit it). You can see it happening if you use it on thick oil paint, but anything thinner won't make much difference. A handy work around for erasing specific brush patterns is to add the design on a separate layer then either turn that into a stencil or use the magic wand to grab the shape of the selection and switch layers to delete paint.