I know this is beta, but you should be aware that in this version, when using a Wacom tablet the brush tool remains at 100% hardness regardless of brush properties settings. It does fine when editing with a mouse.
Make sure that you've set the correct brush settings when working in Ps Web, look in the Advanced settings for your brush to set Use pressure for size or opacity.
Hardness is not an option for brush settings in Web or Desktop.
Let us know if these work, or if hardness is moreso what you're after regarding pressure.