The Father saw it fitting

For it was fitting for Him, for whom are all things and by whom are all things, in bringing many sons to glory, to make the captain of their salvation perfect through sufferings. For both He who sanctifies and those who are being sanctified are all of one, for which reason He is not ashamed to call them brethren, saying:

“I will declare Your name to My brethren;
In the midst of the assembly I will sing praise to You.”
And again:
“I will put My trust in Him.”
And again:
“Here am I and the children whom God has given Me.”

Inasmuch then as the children have partaken of flesh and blood, He Himself likewise shared in the same, that through death He might destroy him who had the power of death, that is, the devil, and release those who through fear of death were all their lifetime subject to bondage. 

For indeed He does not give aid to angels, but He does give aid to the seed of Abraham. 

Therefore, in all things He had to be made like His brethren, that He might be a merciful and faithful High Priest in things pertaining to God, to make propitiation for the sins of the people. 

For in that He Himself has suffered, being tempted, He is able to aid those who are tempted.