In Pakistani weddings I have never seen a woman in bikini or even a skirt for that matter. As you said the choice is ours, you may become hard liner or enjoy the small pleasure of company of your nears and dears.
BTW everything depends on the intentions, the men who like to ogle women or vice versa can do that everywhere and in any kind of dress its not restricted to wedding parties only.
A Muslim women doesn't need to be scantly dressed for it to be inappropriate (Islamically speaking)... attractive shalwar qamiz, makeup & perfume aren't really allowed either infront of na-mahrams (as it is clearly stated in the Quran).
If following the Quran means that one is a hardliner, then so be it... at least those that chose to do so have a good "intention".
and just coz someone does xyz outside the party arrangements then thats their choice, it doesn't mean the host is obliged to cater to their ways of living at the function too.