You don't have to take any one else into consideration. The gear choices we all make are ours and ours alone, period end of story. My question for you is this: since an octo/spare air is something we wear totally and completely in consideration of others that we dive with, then given your statements why do you bother to have one at all??? I mean, you aren't the one using it, it IS for the rest of the diving world if needed, so why not make it easy?? If you run out or are low on air another reg on the same "out of air" tank wont do you any good. Since you don't want to "consider" other divers, why not get rid of the spare air/octo and strap on a pony bottle????
I do use an octo out of personal preference...I "prefer" to make it as easy as I can if someone's life is at stake.