I actually wish they'd go back and give them all evos. The evos don't have to have the Raichu treatment either - they could still evolve to what would work as a mascot. Look at Minccino -> Chinchino for example of what it could look like. It's still giving the same vibe, it's just... stronger.
There is more than just Good and Evil, Light and Dark, Black and White. There's a myriad of colors that you won't see if you look at the world in two extremes.
I think the idea is to not run into the Pikachu->Raichu problem. That being that one of the primary advertising pieces isn't fully evolved. Honestly if they could go back I feel certain they wouldn't have Pikachu evolve.
The ironic thing is though, that since they won't actually retire Pikachu from the limelight, the pika-clones serve no purpose other than to remind you of Pikachu. Which both does the job of making people think of pokemon, but also keeps the clones from being less than Pikachu.
That's what I was afraid of, and it's too bad that stupid things like that keep them from being useful. Emolga especially had potential, they could have given it a pre evo at least.