In a Hive on MR job, all the job properties are put into the JobConf, which can then be viewed via the MR2 HistoryServer's Job UI.
However, in Hive on Spark we are submitting an application that is long-lived. Hence, we only put properties into the SparkConf relevant to application submission (spark and yarn properties). Only these are viewable through the Spark HistoryServer Application UI.
It is the Hive application code (RemoteDriver, aka RemoteSparkContext) that is responsible for serializing and deserializing the job.xml per job (ie, query) within the application. Thus, for supportability we also need to give an equivalent mechanism to print the job.xml per job.