I was just thinking about how console naming has remained consistent between the Japanese and US version of a console for quite some time. I was trying to pinpoint the time when this transition took place and think a bit about why this happened. As best I can recall it was the Saturn/Playstation era where Sega/Sony picked just one name to represent their consoles world wide (internal code names notwithstanding).
Explaining "why" this transition took place is a little more difficult for me. I suppose there were efficiencies in marketing and packaging to be realized by using one name for a console, but that doesn't quite feel like enough. After all, ad campaigns between Japan and US would still be very different even if a console had one international name. But I wonder if there was some macro trend in gaming habits or the market that also contributed to this change. Perhaps you could drum up North American interest in a console by launching the same-named Japanese version - it would be much easier for a consumer to understand "the Playstation is arriving this fall" vs. "the mega drive has launched in Japan and will become the Genesis when it arrives in the US"