When people needed to replace their front doors and storm doors they realized that they don't make the older ones that size anymore. Front doors are already expensive to replace. Most of my neighbors got new front doors and didn't want to spend the extra money to have the storm door built and replaced.
I got mine replaced years ago when I happened to work for a door manufacturer and they made me two doors and installed them front and back for a very good price. Good perks.
I love the extra security of a storm door and my pets love looking out the door. I don't open my door to strangers but a lot of people still do and that would make me very nervous.