Yes, there are better solutions. Although the input pin is protected, the current drain when the processor isn't powered and the switch is in the ON position is (3.3-0.5)/10000=280µA.
EDIT: Here's an improvement (using just passive components). 2.8µA max for 3.3V battery with switch ON. This is pushing the limits of what can be done using just passive components. Might need to use shielded cable or twisted pair if distance to battery or external noise sources are significant.