Is this a question or a criticism?
From the Rise of the Empire rule book:
LEADER REROLL ACTION
When using cinematic combat rules, leader tactic values do not dictate the
number of cards players draw at the start of combat. Instead, as a combat
action, a player can choose to reroll a number of his dice up to his leader’s
tactic value in that theater.
All dice are chosen and rerolled at once. Each die can only be rerolled
once per attack using tactic values. If a player has multiple leaders in the
system, he uses only the highest ground and space values of his leaders in
the system. A player can use this action once during each of his attacks.