Adam,
'But I was wrongly relaxing a bit before I fully knew what BS entailed'
Indeed you were wrongly relaxing. May I suggest that assuming ATC will do some of your work for you in lieu of being alert, irrespective of the service you are receiving, is wrong. The pilot is responsible for the safety of his/her aircraft, not ATC. The service ATC provides is an additional safety feature, not a replacement for lookout and good airmanship.