If we all now are adults? Being physical adults does not mean we are adults according to God ready and able to partake of meat rather than milk:
"I have fed you with milk, and not with meat: for hitherto ye were not able to bear it, neither yet now are ye able.
For ye are yet carnal: for whereas there is among you envying, and strife, and divisions, are ye not carnal, and walk as men?" I Cor 3:2-3
You my brother may not be carnal, but some Christians likely are. They are still only capable of eating and digesting milk. We agree that they should be moving up from there, but too many, I believe, are satisfied with standing still even though eventually that is the way of stagnation and death.