Pujya Bhaishri describes the philosophies of incarnation in-depth on Day 4 of the Knoxville, USA, Bhagavat Katha.
If the Lord is all-powerful, is He not free to and capable of expressing Himself just as you or I are doing so? We are not the body. We are the soul which is ever unmanifest and eternal. Yet we have accepted this body made of material nature to express ourselves with. If we are capable of expressing ourselves in such a way, then why can’t That Highest Reality do the same?
Some people are beset with doubt and wonder what that means for the rest of creation when the Lord manifests into a specific form, such as Ram or Krishna. During that timeframe, the all-expansive essence, That Highest Reality remains intact.