I imagine it was because there was no need to "raise up posterity" like there was in the time of Joseph Smith. Probably a big factor was that in those early days humans routinely lived to be 800 to 900 years. There was a lot more time to reproduce back then. Also since God/Adam only brought "one of his wives" with him to this earth, he probably dropped off his other wives on other earths so they could be populated. In any case you can be sure that the answer to this question "is not essential to your salvation"
There was no rush, since god knew ahead of time that he'd be wiping up the mess of a world wide flood in just a couple 'o millenium and starting over anyway.
Also, with no other men around, there would be no "plausible deniability" for Adam/God like there was for Joseph.
Look at all the shit Joseph had to take from Emma...(and she knew very little) why would God/Adam put up with that from Eve? He could just teleport himself to other earths, and hook up with his other wives where Eve would be none the wiser. How peaceful would the Garden of Eden been if Eve knew? It really made no sense to bring more than one.