Thou Must Be Joking Me.
First off, I'm one of the more modestly dressed women you'll ever meet. If I dressed any more modestly, I'd be an old lady or a nun. (This from my mother, who's also one of the more modestly dressed women you'll ever meet. But I don't even wear lipstick.)
Second, I do support those who choose to step away from the world and pick out a higher standard. If you want to wear Wholesomewear, then yay for you.
But, much as I respect modesty, I refuse to take this kind of stuff seriously as anything other than as a personal spiritual exercise, or one maintaining an ethnic/religious identity. If I wear a one-piece bathing suit without a skirt, I'm not exactly showing everything I've got to the world. Heck, if I wore a bikini I'm sure I could and would pick one that wasn't particularly revealing. (Okay, it would reveal that I have an enormous gut, but I don't think that would entice any men into sin. More likely to drive them into a monastery than anything else -- hey! Bikinis for Vocations!)
It's all very well to compare swimming suits to underwear; but when it comes right down to it, the semantics of a garment matter just as much as its actual form. Many men would be embarrassed to stand in front of strangers in their boxer shorts. Very few would be embarrassed to do the same thing in swimtrunks. Both garments cover similar amounts of skin, but they are made for different purposes. Everyone knows that swimtrunks are not intimate garments, but public ones. Every maker of swimtrunks designs them with liners to preserve men's modesty and the trunks' opaqueness. Similarly, women who would be embarrassed to be seen in front of strangers in a regular bra aren't embarrassed by a sports bra, because it's designed for a firm and flattening hold and total opaqueness. Same thing for a swimsuit. It's not a single layer (unless it's a really cheap suit), it's not transparent (ditto), and it's not intimate.
Conversely, if I climb out of my fitted business suit, hose and heels and change into a long-sleeved, ankle-length thick woolly bulky nightgown and huge slippers, I feel that I am less covered than I'd been during the day, even though the square footage of skin exposed is far less. If someone should come to my door while I am thus in deshabille, I must put on a robe to maintain my modesty. The semantics of the clothing trumps their actual appearance.
Modesty is restraint, not ostentatious nonconformism or conformism. Modesty is acting naturally, not teasingly. Modesty is just plain decency. It's a virtue of minimalism, and if you have to think about it too much, you're probably mistaking shyness or personal style for modesty.
I've been in the SCA (medieval recreation group), and I've seen women clothed in voluminous garments from head to foot, with sleeves that covered even the hands, having no trouble at all being immodest. I've seen women wearing burqa doing the same. (And not just in play, either. There's a segment of the SCA that's a strong family group; and then there's all the unattached college kids, who are often out for other things. As the song says, "If ye cannae get laid at Pennsic War, ye cannae get laid at all.") So I'm hardly convinced that summer's bare arms and legs are to blame for the sins of modern society.
This site's got a pretty decent "outfit test". (It's pretty much what your mom taught you about finding clothes that fit.) However, its claim that the Church never had teachings about clothing until the twentieth century...is wrong. Can you say "sumptuary law"? As for other sorts of immodesty, there were edicts handed down about all sorts of pre-modern fashion crimes. Lessee...off the top of my head...the pointy shoes called poulaines, when the points got stupidly long. (Note the "under pain of cursing by the clergy".) Horned women's headdresses. The infamous sideless surcoat, or "Gates of Hell". (Check out the lady on the side who's wearing a gray surcoat trimmed in white. As you can see, the tightly laced-up kirtle underneath reveals the lady's figure in detail.) So if we were wearing medieval gowns today, we'd still see women posing; they'd just pose like this.
Not liking Britney Spears' fashion choices doesn't mean you have to promote total coverage bathing suits. (Which actually are probably coming, but are not at all Wholesomewear. Today's total coverage competitive bathing suits are as skin-tight as today's running suits, as you'll get a chance to see in the Olympics.) There's a happy medium -- really! -- that won't make other people keep asking you, "Are you hot?" or tell you about their cousin who also had horrible burns over twenty percent of her body. (Wholesomewear really does have that "covering up scars" look.)
However, if folks want to be concerned about modesty, I suggest they start with the Scotsmen. Those immodest Celtic barbarians not only wear kilts that bare their knees, but also let it be known that some go bare beneath them. Now that's a custom bent on inspiring lascivious thoughts!
But if we do go back to total arm and leg coverage and nothing but skirts, I ain't wearin' hose or slips ever again. Give me a nice comfy shift or chemise any day....