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Also Guardians can do the floaty electric ball at the Guardian sites so there's (kinda) prior art.
There is a difference between letting something float and having something attached to a spaceship without physical connection - especially if the engines are attached.
The force holding the spaceship together has to be stronger than all possible acceleration forces in all possible directions.
And it makes absolutely no sense, why create a highly advanced technology to accomplish something that a bit of metal or other physical materials can achieve cheaper and easier?
If I think about it, that's the main reason for the slight frowning upon "forcefield attached wings/engines".