I think Chaya has hit the nail on the head for me in terms of understanding why I'm not likely to ever try it or like it.
Okay so I am married and monagamous and all that yes, but for arguments sake say I was either single or someone who shagged around looking for a bit on the side - I would seek a bit of build up and sexual tension, would want to be pursued but in a non sleazy way, and get to know and maybe not love but lust after the person before I had sex with them. This (I presume) is not really possible at a swingers club because even if you were a regular and gradually got to know someone, its so "out there" in terms of your intention being there in the first place that it would kill the mystery and ruin the build up.
I don't feel offended by the term mundane either, just as I dont feel like attacking the swinging lifestyle but realise why its probably not for me. I dont feel insecure about my sexual preferences - it is fairly "mundane" in terms of criteria when you think about it - making a decision (and backing it up with a contract of marriage) not to intend never to have sex with anyone else ever again. On paper, that sounds about as mundane as it can be, sexually.
In practice its not, in that when you are in the moment and day to day life it doesn't feel mundane, though there are aspects of it that probably are, but that's okay, and if it wasn't, it might be too much hassle/preparation/emotional rollercoaster. If that makes sense! Depending what else is going on in your life at the time (kids? illness? work? etc)
I have vanilla sex too sometimes! Vanilla is nice! I wouldn't want the same flavour all the time though and I'd hate to be told it always has to be vanilla forever. Surely its about choice a bit too.
What a ramble - I think what I'm really saying is each to their own and I tend to agree that nobody should really feel the need to attack anyone else's choice or be offended by anyone else attacking their choice...