Because Lightroom doesn't offer the option to move files off an SD card (vote for that capability here), I never import photos directly from an SD card. However, I often have an SD card inserted into my computer's reader (it's usually empty because I've just moved the photos somewhere Lightroom finds acceptable to move the photos from instead of just copying or adding them). This means Lightroom's import dialog always defaults to the SD card that I never use.
Lightroom should provide an option so set a default import source folder ("import from" folder). Even defaulting to the last used import folder would be nice.