Some folks assume that the creation of fastpass+ means that all of a sudden, the regular fastpass service will disappear. That is 100% false. Disney is working to make the parks more streamlined. To avoid the "dad is going to run to Everest to get fastpasses then meet the family at safaris." Instead fastpass plus enables guests to book attractions in advance. To plan out their attractions and to organize their day.
To those who do not use it, fastpass plus will not affect them as a balance is put in place between the fastpass plus users and the guests using regular fastpasses. Now granted, the fastpass is used as often as possible to help the attractions themselves to understand the demand for an attraction at a specific time. That way, the waits are less miserable and much shorter. It also makes planning easier for shows and other smaller attractions. If you would rather not be as planned, fastpasses for the larger attractions are available without worrying about other smaller attractions. Its that simple. It allows you to customize your vacation. I know a ton of people who would love to show up at Toy Story Mania at 5pm and already have their fastpass ready to go, not dealing with a standby line because they weren't there at park opening.
Also, if you use the fastpass plus system, its actually very easy to be flexible with the times. During the original fastpass plus test at magic kingdom, they had several machines set up so that guests could access a record of their attractions and switch them if they needed to or wanted to.
Also, the ability to have your child wear a wristband instead of carrying a key around for the room? Talk about a blessing. If the Kid can go grab something from the room and not have to worry about losing a card, its genius. They can use the disney dining plan and everything with the wristbands. Its a fantastic idea.