I think it's a valid question from a position of any given skeptic.
I really don't buy the oversimplified answers like "If he didn't leave then Holy Spirit wouldn't come", Or "He left because the mission to spread the Gospel had to be fulfilled", or to "Prepare a place", again neither make a lot of sense in a scope what Christianity is and what it expects.
The question is whether this world is better if Jesus is there for all to be able to experience apart from some "feeling" or a book narrative? It wouldn't make Christianity to be so doubtable. Every Thomas out there could visit a 2000 year old dude with holes in his hands and believe.
Why leave without a trace, and except leave the world with a story and a promise of hope.
It seems like a good excuse to mask the reason as to why Jesus is not here. "Well, he was here, but you've missed him by about 2000 years, BUT he's coming back soon... so just wait and read this book about him".
Perhaps there are other reasonable explanations, but what would these be? What do you think?
He didn't leave without a trace, but I get what you mean.
Let's look at what His purpose was, and basically who He is.
1. He is the Word of God. Anytime someone has spoken to God, seen God, or was moved by God's voice was interacting with Christ - the literal living Word of God. As He said, if you have seen Him, you have seen the Father. And, recall that no man has seen God
the Father and lived. They saw Christ - especially in His "white raiment" of light (transfigured/in His glory.)
2. The patriarchs and prophets knew this about Christ. They also knew He would choose to become human to redeem us. This was reconciled easily with them.
3. His mission as a human on this planet was to defeat sin, and death - something Adam failed to do for all of us. Christ did that - and while it would have been wonderful for Him to stay with us forever, He still has a job to do.
3a) Christ still remains at the right hand of God until all of His enemies are made His footstool.
3b) Christ and God sent the Holy Spirit to comfort us while He is gone, and His enemies are made His footstool
3c) Christ, first, is still the Son of God, and the Word of God. He has work to do (all things were created by Him...)
3d) If Christ stayed (especially like His disciples wanted,) then the fulfillment of 3:15 wouldn't be complete. The enemy must fully drive to apostate and evil and manifest all of its imaginations (allowable) so that Christ can completely and utterly
raze the evil. That means He allows the "downtime" of the ignorant evil entities continue to try to compete as if they have a chance of winning, when they have already lost. It is a further of shame that will be brought to the enemy - to know they labored for nothing, and truly lost.
4. Christ promised to come back to rule - as He will. And, so it will be (actually, so it is.)
5. Christ has the right to approach the throne of God, to transsubstantiate into human, or to
be Himself - the endowment of everything God has given to Him.
6. We humans have to show what we learned, what we believe, if we have faith, and how we will live given everything that has happened, and everything He has done - so that we all can be judged
justly.
7. Firstfruits will be borne from the ashes of the Enemies attempting to destroy the entirety of creation - like impure gold burned to rid it of impurities. These "firstfruits" will be partakers and "partners" in the ministry of Christ, the stand against the evil (one,) and witnesses to all of this - including the eventual return of Christ.
8. In all honesty, it wouldn't matter if the Word of God Himself was right in front of people's faces and showed them His holes in His hands... it
barely worked for Thomas. So, Christ likely knows appearances by Him will not affect the overall faith (or, at least it shouldnt.) The disciples of Christ were around Him almost 24/7, and they still had to hear it from Him who He was. And, these were people chosen by Him.
9. Christ is "in contact" with His people. They know Him.
10. We do not have (close to) any of our priorities straight concerning our spiritual relationship with God.
Just think about how the patriarchs felt hearing the fresh prophecies of Christ, not being able to perceive Him themselves,
and, they didn't have a holy spirit to comfort them. Yet, they still had faith in Him. That is big - something we can learn from. They had it really bad, and it would have been very easy for them to go into flashy spirituality (like witchcraft) that seemingly yields results, rather than wait. In fact, many Hebrews did do that.