I also miss the old Soraka kit, but I play her a lot even now. Soraka can still do quite a bit of damage, but it is loaded in the bonus Q damage and both E procs, making it difficult to access. I recommend taking Soraka with another champion with enough crowd control to keep one or more people in your silence field long enough for both procs. If you can hit that and the center of your Q, you have a total AP ratio of 130%.
I almost always take Ardent Censer on Soraka, which helps her team dish out a lot more damage in fights. Even if she isn't obviously doing the damage herself, as old Soraka did, you can still contribute quite a bit of it to team fights. If you really want to do damage, you could always build a spellblade item. She casts often enough that you will essentially always have the empowered auto attack while fighting.