It's not the 20th Century.  No longer must we run outside and climb down stairs in the driving rain.  And with the legion of smart people keeping watch on the skies, we dwell in a storm shelter for a much shorter duration, meaning that we can have a safe room that is not too bulky in the home.  Remaining above-ground has several notable benefits including accessibility after the storm.  First-responders are likely to see more quickly a shelter that sticks out like a sore thumb, rather than hunting under random debris fields for you.

(Shelters come in various cosmetic variations.)