Yes, there is a very real advantage. Take this hypothetical, but very likely scenario. You are storing something Very Bad(tm) that you absolutely do not want the police to find. Your opsec is pretty good, but you make a single mistake online, and the cops are on their way. It's 4 AM in the morning, and they burst in with a fresh warrant for a no-knock raid. You stand by helpless as they take every single device in your house, all of your dozen flash drives and SD cards, your hard drives, laptops, etc.
Days later, they confront you again, asking you if any of your flash drives are encrypted with something called "TrueCrypt". They know you are tech savvy enough to use it, but they also know you are tech savvy enough to wipe your flash drives. They have no idea whether or not you encrypted it, or you simply wiped it. They can't force the key out of you, they can't lock you up for refusing to give them the key, and most importantly, they can't spend a long time trying to crack all of your dozen either-wiped-or-encrypted devices because spending too much time on a single case gets investigators in a lot of trouble.
Because you used TrueCrypt, the devices which you simply wiped blend in perfectly with the devices you have encrypted. You're let free after the cops are reprimanded by an angry judge who regrets signing the warrant in the first place.
This example is especially potent in countries with mandatory key disclosure laws, where if they have evidence that you are hiding encryption, they can lock you up. If you can claim that you simply wiped your hard drive and it's all random data (which is especially plausible if you have a spare CD with DBAN burnt on it lying around), then no matter how much they want you, they'll have a very hard time getting you locked up. But even in countries without such laws, it's still an extremely good idea to prevent your adversary from knowing where to focus their efforts, or even knowing that they have found what they are looking for.
Note that this "TrueCrypt-Paradigm" is much more effective on entire disks. It is significantly less effective when used as individual volumes, because it's not that easy to explain away a large, random file sitting on your hard drive, especially if TrueCrypt is installed on that system. Not as easy as it is to explain away a hard drive with random data, where even if TrueCrypt is installed on some computer in your house, it still isn't even close to enough evidence to point to that specific hard drive being encrypted rather than just wiped.