This is a really interesting idea and it just 'sounds' right to me, sadly though I feel awful because I didn't have this attitude when my now 10 year old DS was small, he was only nearly 3 when DD was born and I really regret the high expectations I placed on him
My DD has been 'treated' much better and if I have another I'm sure I will be even more in line with this thinking, What a shame for my eldest
Also I wasn't a christian( and have been gradually becoming a better parent since)until he was 5 but I am trying to make up for 'lost time' with him