Lois is nearly as iconic as Superman himself. She's the second most well known female comic character in history. She's incredibly important.
The new character could be a villain.
Agreed..if this was a story featuring about his SV days, then you don't call that film a "Superman film", and given that we've had 10 years of SV, with 7.5 years of Lana, yeah, like that's the thing that fans wants to see on the big screen.
I mean:
1. Lois is practically always there when Superman makes his first big public save; in most cases, she's the one that he is saving.
2. Lois is the first reporter to land an exclusive interview with Superman
3. Lois is Superman's biggest public defender.
4. Unlike Rachel Dawes or MJ, she can kick ass when she wants to, and she brings a lot of personality to screen, very fun to see.
I mean like others have said, making a Superman movie without Lois is like:
1. Making the Star Wars Prequels without Obi Wan
2. Making the Avengers without one of the Big Three (CA, IM, Thor) in it.
3. Having Two face without his special coin
4. Pirates without Jack Sparrow
etc.