Almost! Except if you want to store objects/arrays/numbers (localStorage only supports strings), or want your site to work in Safari Private mode (where localStorage breaks), or if you have to support legacy environments with old browsers (like many government services), etc etc etc :)
Except when a value has already been stored previously without JSON.stringify (in which case JSON.parse will throw), or you need a default value if unset (e.g `store.get('username', 'anonymous')`, or ... :) But I also see your point that sometimes the very quick and simple solution can be useful!
Not if you want to store more than few MB (5 or 10 max depending of browsers if I recall).
Not if you want/need an async API.
Not if you need to be able to search your storage.