1. Neither are particularly interested in revenge at this point.
2. Obi-Wan is for all intents and purposes a hermit; Maul is still active in the galaxy and is getting directly involved with the main cast. I, personally, can't justify him ending up on Tatooine chasing an old enemy he doesn't even have current beef with.
3. Maul has had ample opportunities to kill Obi-Wan. TPM. All through TCW from his return, during both TCW tie-in comics they appeared in, up to the Mandalore arcs.
But character motives, or as we know it, PIS, has always prevented him from killing Obi-Wan. Obi-Wan in contrast has never had that kind of ability or resourcefulness. He got lucky once because Maul was gloating. For Obi-Wan to kill Maul there would need to be an element of bullshit I'm pretty tired of seeing.
I want Maul to be killed fighting an equal or stronger opponent; just a simple, badass fight. No bullshit with Maul slipping on a banana peel into Kanan's lightsaber. It's not really asking for much; let Vader or Sidious do it.
__________________ “The galaxy must experience the pain of death and the rapture of rebirth as I have. I will bring chaos. It is time for war.”
Whatever he's been up to--it has likely been part of Palpatine's plan: http://i.imgur.com/zHe4kWq.jpg
...Or at least, that's what Palps alluded to. /shrug
"The Grand Admiral was smart and subtle, but never used his brilliance to show up or humiliate anyone.
He demanded results, but never perfection, and had amazing stores of patience for those who were truly working to their fullest ability.
It was a pity Thrawn's style of leadership hadn't spread through the rest of the navy.
If that happened, he suspected, the Empire would stand forever."