Here we go again...
First off, it appears that whatever happens, the fanbois will only ever praise something if Apple does it first, which in this case, is the 64-bit thing. Should Samsung have done it first, they would have derided it as unnecessary. Now that Apple HAVE done it first, everyone else will now 'merely be copying them'.
He's been dead a long enough time, but it appears Old St. Steve is still spinning fast enough in his grave to keep the RDF fully powered up for another 5-6 years.
So... 64-bit CPUs in a phone. Practical? Who knows. Nice to have? Probably. Essential to the modern world? Not really, no. When all the world+dog seems to do on these things is text, call, peruse Farcebook and the like, and listen to music... very few people will ever seen any real-world benefits to this. That said, progress happens in odd ways. Just because it's no good to us right now, doesn't mean we won't be seeing things taking advantage of it later on. I'm just not convinced we're at a point where we need full desktop power in a battery limited device.
About the only real benefit to anyone is the manufacturer of these chips. If they can shift more of their designs to 64-bit, and drop the older architectures, they'll have less variants to keep track of, and can focus more on improvements and the like.