Messages app on iOS is the most frustrating app I have to use often and Apple doesn't allow any alternative as well. There is no way to star/pin certain messages in it. It doesn't allow copy-pasting partial text in a message. Results of searched query are often not what I am looking for. Finding historical messages in some date range takes minutes.
Many other Apple-built apps and products (especially those that cannot have any 3rd-party alternatives) are horrible to use.
Many other Apple-built apps and products (especially those that cannot have any 3rd-party alternatives) are horrible to use.