That was pretty much Maul's role by intention by Sidious in pre-TCW canon. He was an assassin that Sidious didn't have to worry about getting backstabbed from. And I'd argue that Maul did have personality and character back then, even if it was a bit flat.
Yes, but this is what's utterly fascinating about the Rebels take on Maul -- he's had enough time for introspection in retrospect to
realize just how much Sidious was always using him. In many ways, at this point he's a tired old man who wants to rest, but at the same time, he's still a Dark Sider and peace is anathema to him. He's still absolutely driven by hate, even though he can also *see* how much it's destroyed him, and he hates
that as much as he hates Sidious. In the end, Maul *almost* doesn't attack Obi-Wan on Tatooine. But he can't
quite bring himself to let go the hate, and so dies.
That scene, as I said, is one of the most amazing moments in all of Star Wars, especially in the subtle details. When they're facing off with each other, Obi Wan starts in the same cautious center guard he used in his classic
A New Hope appearance. He then very deliberately switches to the Soresu guard he used in the Clone Wars (the flashy one with his free hand pointing forward), back to center guard, then to the high shoulder guard he used back in the Phantom Menace. Maul then uses essentially the
same attack sequence he used against Qui-Gon all those years ago in Phantom Menace, but Obi-Wan (despite being old and "pathetic") easily and lethally counters it. But Obi-Wan then holds Maul with genuine sadness as he collapses and dies; Maul's last words are asking if the child Obi-Wan is guarding is the Chosen One and Obi-Wan
tells him yes, giving him a measure of peace and closure as he passes away knowing Sidious will be brought down in the end.
Rebels was overall much more of a kid-oriented series than Clone Wars, but it had moments like that which were
incredibly deep.