(If you want to get really hardcore fantasy nerd about it, Wikipedia has a decent amount of background on the Second Age.)
Even in the Second Age, though, jerky ol’ Sauron is around and causing trouble.
Give me something new — even if it is technically something old, set way before the films.
And the Second Age is when Sauron first forged the One Ring in the fires of Mount Doom, so the title will remain accurate, even if many of the characters will be different.