The remote wipe would be equivalent to a format so you may be able to get some data back but most of it would be unusable. I don't think Apple can do much about not having a backup. What Apple probably needs to do is have a popup to remind people to backup when they switch on the Find My Mac feature. But I doubt they can do more than that.
Even if Apple could recover the data by doing so they would be admitting their remote wipe feature is worthless.
I rather doubt they will add a "I see you have enabled Find My Mac--you better back up your system because we will give any random idiot who calls in access to wipe your hard drive. Thanks for choosing Apple!" popup, though.
On the iphone, the file system is always encrypted, and the encryption keys are stored on the device, themselves being encrypted with your PIN/passphrase. To perform a remote wipe, it only needs to zero out this single block containing the FS keys, making the whole FS unrecoverable since the keys are gone.
I wonder if the same thing happens on Filevault2. In that case, Apple's only choice would be to rent some serious GPU time at NSA or something...
The remote wipe would be equivalent to a format so you may be able to get some data back but most of it would be unusable. I don't think Apple can do much about not having a backup. What Apple probably needs to do is have a popup to remind people to backup when they switch on the Find My Mac feature. But I doubt they can do more than that.