because..
Virus. Large in comparison to a sd card.Files may get corrupted.Storage space is limited.
Speed is the main disadvantage.. when we include more and more application speed ll decrease.
Input Devices provide input signals to Computing devices. There can be disadvantages for a particular type of Input Device such as Mouse, Keyboard, Pointers etc. Nonetheless without Input devices...
cost is higher, longer verification time, require special housings, don't work well in exterior environments