Contraception is not perfect. If you are on birth control, and you take it every day, you can still get pregnant, it's just unlikely. If you have an IUD, you can still get pregnant, and even worse every pregnancy is more likely to be life threatening. And of course, condoms can break.
As for having less sex ... that's an interesting thing to say ...
This is legit the movie I shit on most. I hate it so very much. It's not the plot exactly, it's two things:
The tech accuracy is so bad. I won't go into everything but they go out of their way to say shit that doesn't make sense. My favorite example is that the AI is just a big floating orb and they feed it data through infrared, the slowest communication method available. Like they didn't have to say infrared, they chose that.
The product placement. Again, a lot of examples but my favorite is how at the end he shows up with Guitar Hero and the kids are like "Yay Guitar Hero that's the best game ever."