Plus the problems of that world could easily be cleared by just a single person. An entire party is just overkill. I mean, I just rewatched the movie. 

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Part where WALL-E gets crushed? Easily averted by a person who is capable of walking and getting the plant in there and the thing could easily be raised with the strength or magic of any of the party members enough to get the plant in there. 

The Robot warning sign dudes? Easily defeated by anyone. 
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