Aging off in my game _ I control all sims aging.
As to why - well personally the best aging we ever had in Sims was Sims 3 Epic aging as I love a long slow aging game so I could really do the game perfectly for aging in that game. I tried the longest aging Sims 4 offered and way too fast - but with the ability to easily control aging on all the Sims in my game including the ones I don't play even - I turned aging off for everyone. The households I actually play which is sometimes as many as 35 families or more in some saves - I allow sims to have birthday cakes or parties to age. The households I do not play - I age up through manage households but will not favor them unless I have future plans for anyone in those households.