Ah, but if the Jesus hadn't resurected, the diciples wouldn't have stuck with what Jesus said. In Jewish belief there were to be 2 Messiahs. The Kingly Messiah who is to come down and set up his kingdom, and the Suffering Messiah.
The Suffering Messiah is prophecied in the book Isah:
Isaiah 53, 1-12 NIV
Isaiah 53
1 Who has believed our message
and to whom has the arm of the LORD been revealed?
2 He grew up before him like a tender shoot,
and like a root out of dry ground.
He had no beauty or majesty to attract us to him,
nothing in his appearance that we should desire him.
3 He was despised and rejected by men,
a man of sorrows, and familiar with suffering.
Like one from whom men hide their faces
he was despised, and we esteemed him not.
4 Surely he took up our infirmities
and carried our sorrows,
yet we considered him stricken by God,
smitten by him, and afflicted.
5 But he was pierced for our transgressions,
he was crushed for our iniquities;
the punishment that brought us peace was upon him,
and by his wounds we are healed.
6 We all, like sheep, have gone astray,
each of us has turned to his own way;
and the LORD has laid on him
the iniquity of us all.
7 He was oppressed and afflicted,
yet he did not open his mouth;
he was led like a lamb to the slaughter,
and as a sheep before her shearers is silent,
so he did not open his mouth.
8 By oppression and judgment he was taken away.
And who can speak of his descendants?
For he was cut off from the land of the living;
for the transgression of my people he was stricken.
9 He was assigned a grave with the wicked,
and with the rich in his death,
though he had done no violence,
nor was any deceit in his mouth.
10 Yet it was the LORD's will to crush him and cause him to suffer,
and though the LORD makes his life a guilt offering,
he will see his offspring and prolong his days,
and the will of the LORD will prosper in his hand.
11 After the suffering of his soul,
he will see the light of life and be satisfied ;
by his knowledge my righteous servant will justify many,
and he will bear their iniquities.
12 Therefore I will give him a portion among the great,
and he will divide the spoils with the strong,
because he poured out his life unto death,
and was numbered with the transgressors.
For he bore the sin of many,
and made intercession for the transgressors.
Also Jesus himself stated that he would return after 3 days:
Matthew 16, 21-28 NIV
Jesus Predicts His Death
21From that time on Jesus began to explain to his disciples that he must go to Jerusalem and suffer many things at the hands of the elders, chief priests and teachers of the law, and that he must be killed and on the third day be raised to life.
22Peter took him aside and began to rebuke him. "Never, Lord!" he said. "This shall never happen to you!"
23Jesus turned and said to Peter, "Get behind me, Satan! You are a stumbling block to me; you do not have in mind the things of God, but the things of men."
24Then Jesus said to his disciples, "If anyone would come after me, he must deny himself and take up his cross and follow me. 25For whoever wants to save his life[h] will lose it, but whoever loses his life for me will find it. 26What good will it be for a man if he gains the whole world, yet forfeits his soul? Or what can a man give in exchange for his soul? 27For the Son of Man is going to come in his Father's glory with his angels, and then he will reward each person according to what he has done. 28I tell you the truth, some who are standing here will not taste death before they see the Son of Man coming in his kingdom."
Had Jesus died and stayed dead, the diciples would not continue to preach that he rose. Human Nature just plain dictates that. There would be nothing in it for the disciples, or anyone, if they followed a dead savior.