..... Should training (of whatever kind) be aimed at increasing or decreasing moods of frustration and anger?
The FIlipnos would say "decreasing;" they have a saying, "play to learn." The idea is you lear better by taking the pressure off and having fun doing it -- they PLAY. My Kali instructor says Guro Dan Inosanto has said "Whatever you are doing, make a game of it." And WRT Indonesian arts you see the phrase "Silat Player." It's not that they don't take what they're doing seriously, they do, very much so. "Playing" means to study without gettig PO'ed. And Thai Boxers "play" when they spar all day in a hot and humid country: they go at lower intensities so they can learn from what you are doing. My Kali instructor has set the same goal for sparring -- if you can enjoy it, then you start to learn from doing it.
All of this neatly backs up O Sensei's "Always train in a vibrant and joyful manner," doesn't it?
Anger and frustration can backfire, too -- you get mad, you don't want to go to certain classes and/or do certain things. I have that problem with sparring: My perception that I am always a "punching bag with legs" leads me to not like it, and that gets in the way! Especially when I spar with someone who hits pretty hard and is fast enough to get past my defenses. I have to work through that to get anything out of it.
The consensus, then, from the broader martial arts world is DECREASE. Or, to put it another way, if you're not in love with what you're doing, don't do it.