Well, Atonement is baseline ans as such yes, you'd be bad for ignoring it. BUT. Atonement stacking is a bit different now a days. You can glyph Holy Fire to make it instant and penance the boss for another stack. By using only these two spells, it takes 22 seconds to build up five stacks, which you can then keep up with instant Holy Fires only, and consume for extra healing when needed. You certainly aren't forced to be a smite bot which seems to worry you.
I think you might like disc healing surprinsingly much now a days. Absorbs are stronger than ever; Mastery is our strongest secondary stat (after spirit ofc), and it's a very strange encounter when absorbs make up less than 50% of your healing. Spirit Shell (disc short raid CD that replaced Divine Hymn for us) converts all your healing in to absorbs for 15 secs on one minute CD. If that isn't the most awesome thing for PoH spam-lover, then I have no idea what is