Pasta is not a cooked product in the store - it is a raw food. So by cooking at home and dehydrating you get a ready to use product (just like when you cook and dry rice!). Also, it removes the starch so you don't have to contend with starch filled small pots of water that love to flow over.
The other key thing is your pasta is now basically "instant" - it need only soak in hot water for 5 to 15 minutes (depending on how big your pasta is, then drain and carry on. This means no big pot, no messy cleanups and no boil overs.

Also, once cooked and dehydrated pasta has a shelf life of a year or so with no issues. You want it bone dry.

On freezing? You only need to freeze dehydrated foods if they are combined with meat, dairy or oil - as these items can go rancid in storage over time, freezing stops that. But alone, no.