Here are some of the things that I hope Defraggler can have:
Defrag all drives.
Options > Shutdown after Defragmentation complete. - The first two options would benefit people who wants to sleep / go out while letting Defraggler do the job. A shutdown after defragment complete option would round everything up nicely.
Registry Defragmentation - For the sake of being a all-rounded Defragmentation software!
Disk Map Legend placed at the Drive tab (For clarity)
More priority modes on the usage of computer resources: High, Medium, Low, Background modes - The ideal way to defrag the computer is to defrag it when we ain't using it. Why do we need to help the computers save resources when we ain't using the computer? That is why a High priority mode should be added! This way, we wouldn't waste all the excess computing power that our computers have. As for the other modes, it's pretty self-explanatory.
Speed increase! - I've used Auslogics Disk Defrag. Both Defraggler and Disk Defrag are good softwares, however, Disk Defrag wins Defraggler hands down when it comes to speed.