Right now there aren't really that many reasons to use the shelters and i end up not using it very often which is why i think there should be more mechanics in the shelters.
Example 1:
A makeshift shower that can replenish a little bit of health once per tide for free.
Example 2:
A microwave that can heat up a specific type of food that can be bought from the store that replenishes maybe 75% of your hunger.
Example 3:
(I can't come up with more examples but it's weird if there only 2)