From my perspective, it makes sense for Ubiquity to write the 'auto eth0' (or more generically 'auto ethX') for a non-wireless device that it did the install over.
The difficulty is in determining if the user was just doing an install over that interface or would generally expect it to be permenant. If the user is expecting to keep that system plugged in, then adding an 'auto' entry is the right behavior, and *not* adding that entry may well mean the user cannot reach their machine after install.
From my perspective, it makes sense for Ubiquity to write the 'auto eth0' (or more generically 'auto ethX') for a non-wireless device that it did the install over.
The difficulty is in determining if the user was just doing an install over that interface or would generally expect it to be permenant. If the user is expecting to keep that system plugged in, then adding an 'auto' entry is the right behavior, and *not* adding that entry may well mean the user cannot reach their machine after install.