Should memories recalled as the result of hypnosis be admitted as evidence in court? Why or Why not

Short answer: legally, possibly. In practice, and as a matter of ethics, almost certainly not.
Legally, the question of repressed memories being admissible evidence at all is highly contentious. See reference for a detailed breakdown of the legal standard for repressed memories in the United States, but the short version is that in most circumstances, its admissibility and weight are determined on a case-by-case basis. In addition, the general attitude of the legal system has consistently moved away from repressed memory as reliable.
Hypnosis compounds that problem. Depending on the court, one of three different standards may be applied to the use of evidence obtained under hypnosis: "credibility," which leaves the question of reliability to the jury; "discretionary admission," which leaves the question to the judge; and "procedural safeguards," which set specific, formal rules about what evidence, under what circumstances, can be admitted. 
Ethically, as noted in the Department of Justice reference below, the question of repressed memory being admissible as evidence is "in flux," after several convictions based on that evidence were overturned after factual evidence proved the "memories" to be false. It is broadly accepted throughout the psychological community that memory is suggestible, and hypnosis by definition places the patient in a suggestible state. Indeed, courts have used the mere use of hypnosis to call into question a witness's mental state.
In the context of a court of law, my conclusion is the same as Paul Giannelli's, whose abstract is cited below: "Unless the advantages of hypnotically refreshed testimony are significant, why add more problems?" In the current state of play of both psychology and the law, the use of evidence based on repressed memories obtained under hypnosis is ethically troubling and pragmatically more trouble than it's worth.
https://www.ncbi.nlm.nih.gov/pubmed/7737764