The toddlers are absolutely hilarious, and they're a part of the base game now, but yah, the whole parenting skill 'n different personality traits that can be encouraged or discouraged are a part of the parenthood pack.
'n apparently that really is Grim, not a sim dressed up as. You can cheat with 'add to the family' when you see him, but he does lose his job as the Grim Reaper then.