why are they obscene ?
Normal male body. Normal male "equipment". Physique is due to hard work on your part.
The suit has a "pouch" for comfort, and I can make out the outline of the head of your cock. Judging by the arc of the bulge, there are a couple of sizeable balls underneath.
So let's try this approach : Anywhere else in the world, at any pool or beach, this bathing suit would be a no-brainer. You would be admired, silently, for your physique and masculinity.
Here in the Excited States of Paranoia, you would be seen as gay, and an exhibitionist, two ideas that scare most conservatives and "christians" to death. However, most people would concede that since you have an excellent physique, you "qualify" to wear such a bathing suit. Then again, there are those who nonetheless would take one look at you, and decide that actually showing the outline of your cock and balls was obscene, and they would either run screaming to the first cop they could find, to complain about being "offended" by your bathing suit, or at least suddenly move their family (shielding the childrens' eyes) and decamp to a spot further down the beach where they could be as far away from you as possible.
So you tell me ... which are the perverts in this example above ?
You look great, mate, and have nothing to hide nor feel ashamed about.
Lost in the "freedom of expression" discussions where it's all about the wearer's right and desire to flaunt or be comfortable or whatever, often justified under the guise of "the natural male body is a beautiful thing and there's not a thing wrong with displaying any part of it", all the while lambasting as prude, unenlightend, or radical Christian fanatic anyone who would dare to object, is the simple concept of propriety.
That's an awesome suit the OP is wearing, and he looks great in it. I have several like it. I wear them to gay beaches, gay resorts, and private parties where it's an adult crowd who are like-minded and appreciative. But not at my Masters swim practices or meets, not at commercial gyms, not to regular beaches, not at the Association swimming pool, and not at regular family parties, although I may wear a regular, classic Speedos to some of these places sometimes, most notably if I'm there to get some laps or open-water yardage in. I'm agnostic, so religion has nothing to do with this. I just happen to think there's a time and a place for everything. I don't shit on propriety, courtesy, and respect. I'm not going to assert an absolute right everywhere I go, if it makes people uncomfortable. Not everyone wants a cock bulge waving in their face, even if it is attached to a nice body, and it's not appropriate for every setting, and people aren't necessarily prude or unenlightened just because they happen to feel that way.
Also, there are local and regional conventions and social norms all over the world, some broadminded, some not. It's a silly argument that because something is accepted in one country, there's something wrong because it's not accepted universally, or in another country. We can't simply pick and choose which standards we think should apply to us and which ones shouldn't. There are places in the world where it's convention to hang gays or stone them to death. How would you respond to some skinheads who feel their rights are being trodden upon because they have to tolerate the presence of gays, and lament the fact they can't kill you, because it happens to be perfectly acceptable in a fair number of countries?
I'm not here to tell him how to run his life, and I don't know if that's what the OP is getting at or looking for, but there's a huge range of male competitive swimwear, from briefs to square cuts to jammers and beyond, in a range of fabrics, from many manufacturers. No shortage of choices that, if sized correctly, will allow even the most hung guy to swim in comfort and still show off his body, and even his dong a little bit, if he wants to, without having to prance around on the deck with the other lap swimmers in a fashion swimsuit that was never designed for hardcore swimming in the first place. In nearly 40 years of competitive swimming, age group and masters, I've never heard any guy complain that he couldn't find a suit to train or compete in comfortably, because he was so hung.