If every PC had a number pad I'd agree but efficiently using the top row number keys for both symbols and numbers is a tall expectation for most users to default to. Doubly so when you factor in holding shift and memorizing the operator locations in that row. A full point and click is a great default IMO, even on PC. I'd also argue in the case of devices with a numberpad you're unlikely to care as much about the wasted UI space anyways.