I think the Russo's like her complexity and the combination of huge power and intense vulnerability, that mixture of danger and innocence, and want to explore that.
The Russo's describe her as being on a growth arc. Vision is a god becoming human, Wanda is a human becoming a god.
Her arc is about becoming a new person, overcoming self-doubt, and growing through friendships.
"Mind powers" would not do much of anything against Thanos, and Joe Russo hinted at "Wanda not knowing the depth of her powers", it's canon that her powers are not understood by anyone, not even Strange. Telekinesis is not a mystery for the Sorcerer Supreme to unravel. Chaos Magic on the other hand would absolutely confuse and shock Thanos, blocking his attacks and augmenting her allies (Hulk punches 1000s times harder, Groot splinters all grow in seconds etc).
She's the only Avenger with a (potential) power set that can counter Thanos.
However her power being connected to her emotions is amped by using such huge power, meaning if Thanos, say, revives Pietro, she would be susceptible.
In the comics Strange fakes her death to trick Thanos, there's a very logical reason to do this as any plan to defeat Thanos would likely require him to think he has won and there is no threat, to let his guard down.
Theoretically Vision could survive within the gauntlet via Wanda.
"Love is for souls, not bodies", thus has another meaning.
Perhaps she loses her "mind powers" and connection to the gem at the end of IW and thus joins Strange to fully learn her remaining mystic powers.