Hi, Andrew —

Only God knows the answer, but some have speculated that he does not reveal too much of himself because he does not want to impose the truth on people, but instead wants to draw people by faith.

The truth is a powerful elixir; if he revealed too much of himself, perhaps some people would be less inclined to follow. Or, he wants people to obtain more reward by believing by faith; there is no reward in believing something which is obvious.

It is true though that Jesus has made appearances to individuals throughout the years.
For example, after his ascension, he appeared to Saul (Acts 22:7). He's appeared to various other saints as well. He's also worked miracles throughout the years.

Eric