I consider this behavior (no squawks when the footprint's pad-count exceeds the number of symbol pins) a useful feature. The present discussion (mechanical pads on connectors) is one justification. Some diodes (2 symbol pins) come in SOT-23 packages (3 pads), and some single (3 pins) or dual (5 or 6 pins) transistors come in 8-pin packages. In these cases, forcing the unused pins to appear on the schematic, only to be flagged "NC", is distracting clutter to me. When importing a netlist I have no complaints if KiCAD throws an error ONLY when the pad-count is LESS than the pin-count.
(I know it's logically inconsistent, but I have the opposite belief about unused connector pins. If a connector has, say, 15 (electrical) pins, I want to see all 15 of them on the schematic - even if I will mark many of them as "NC". I would NOT selectively delete unused (electrical) pins from a connector symbol even if it was practical to do so.)