One of the main reasons why wiring buttons and logic to GND is favoured (and then copied all over the internet) is because of power optimization. - Pulling a pin LOW with resistor to GND costs 0 watts. - Pulling a pin HIGH with resistor to +Vcc costs power. On complex circuits or circuits that rely on batteries this power is very precious. *Other reasons include low EMF generation. On Wireless devices pulling logic high will cause unnecessary cross talk on extremely sensitive RF receivers. On such transceivers there is a GND plane used to filter noise and this is where all logic gets pulled down to. The processor then uses the GND plane to filer switching noises.*