MicroSD memory cards also make transferring files between electronics faster, and a lot easier and more convenient then using a USB cable. All you need is an USB external MicroSD Card Reader to move your files to your files from your computer to your MicroSD card to copy and paste files to and from your MicroSD memory card.
A MicroSD memory card has no moving parts like a hard drive, so a MicroSD card is more likely to not break when dropped on a hard floor surface like wood or rocks.
Another advantage of a MicroSD card is it is removable, so you can take out the memory card, and use a USB MicroSD reader to recover your data to your computer, so if your MP3 player, phone, or tablet becomes broken, you can still recover your files. You can also plug in your MicroSD card into your new Tablet, MP3 player, etc to read your files on the MicroSD card.
I have a MicroSD card inserted on my Kobo Vox's Micro SD memory card slot to add more storage to my 7 inch Kobo Vox color eReader Tablet, so I can carry even more eBooks, music, videos, documents, pictures, and other files to view and playback on a MicroSD card up to 32GB in size on my Vox. This means I have a maximum of 40GB of storage on my Vox if I include the 8GBs of storage which is built-in to my Vox. Having more storage let me carry more files, so I have more files to read, view, and watch even when I'm not connected to the internet. I can also move more files to my MicroSD, so I have more internal memory and SD storage space to install apps, and app add-ons like browser plug-ins to install on my Vox rather then filling all my internal space for music, videos, documents, and app installer files.