As a proud parent of a 'Transformer' cos-player I was having this very same conversation with her.
She doesn't like the super awesome costumes, as it pushes the standard up too high for those without the skills and/or money to keep up with them.
Myself and my wife come from re-enactment as far as dressing up is concerned (although my wife was one of the first cos-players in the UK) and thus are more into getting things right.
In the end, it all relies on what the player gets the most fun from. Be it just a wig, or something akin to a Napoleonic General of Hussars!