I know, I know you have 32 Gb and with the iOS 5 upgrade, you have access to iCloud, which includes 5gb of cloud storage but what if you want more ? ( mkv movies on the go while flying Dublin to Sydney for example ? )
A 64Gb flashdrive this days cost anything between 15 and 40 Euro ( well worth it ) and is handy to carry around but is useless if you can't connect it to your smart phone, isn't it ?
Works for cars isn't it ? How many doors you have in your house but no idea where their keys are ? Hearing a burglar downstairs ? Press a ( master ) button - all doors get locked so no way for him to get in your bedroom or ( back ) out in the street before police arrives ( if ever :P ) . Somebody rings the bell ( and you know who it is ) ... same, press a button and let them in ... and examples are many ?
Question is .... why not ?