I don't care. I don't see why I should care. Riding boots are comfortable - if someone wants to use them as regular footwear instead of riding in them, who am I to judge? It's not just riding gear that people wear outside of the sport, either. It happens in many different sports (or non sports). I have a big thick hockey warm-up sweater that's my favorite sweatshirt ever. I don't play hockey, I wear it because it's warm. I also have an old retired German army jacket (that I'm sure is a long dead style!) I use to ride in (as it's long, but split up to the waist so I can sit down on a horse in it.) I'm not in the German army. I wear it because it's functional and incredibly warm to fit my needs.
I honestly think that those 'riding boots' posted are bought by people who have no idea they're riding style boots. I didn't until I got horses. I know several people who own boots like that, and just like how they look. Many times I've asked after it to find a surprised reaction to the revelation. It's not quite as obvious as, say, soccer cleats would be that they're meant for riding. A few thought they were stylized motorcycle boots.
As for the sexualization.... It happens. With most professions. Look at nurses. Firefighters. Pool boys. Police men. Come halloween time you will see TONS of "sexy" outfits of all kinds of disciplines/professions/you name it. I realize that you're all mostly referring to immodest every-day type riding gear, but still - it can and it will happen. If anything I think it's flattering that people want to dress like a horse person! (Whether or not they know they're doing it!)
Also, I actually got snarked on a few times here at school for being a "wannabe" horse rider. The only real riding gear I have is boots - so I'll be in jeans, some amorphous (probably black) shirt with some band on it (a lot of my shirts are from concerts) and a sweatshirt that's plain. And my riding boots, because they're SO comfortable. Finally after 3 years of use they're showing the wear, but previously I'd wash them before I left the barn so they'd look nice and clean. And three times, I was stopped by a TOTAL stranger who ragged on me for wearing riding boots when I "clearly" didn't have any horses. After all if you live in the city you CAN'T have horses. *eye roll* - so don't be so quick to judge someone on their attire when you don't really know if they do or don't ride