Anything that could possibly make any man have any illegitimate thoughts about a woman should be outlawed.
In Gateshead, they would be rightly appalled at the suggestion of mixed seating, and not only that, but they take the further precaution that the Chassan and Kallah aren’t even allowed to hold hands as they step off the chupah, for that very purpose of avoiding hirhurei aveirah.
Any inconvenience this may cause to the ba’alei simchah pales into insignificance when compared with the ‘kateigor’ of having caused someone to have improper thoughts at your simchah.