Yeah, some are good sex. Some are not. I think it depends mostly on the girl.. a lot of Japanese girls are taught (via porn and otherwise) to just lie there and take it.. which doesn't make for a ton of fun. In longer relationships you can train 'em up though!
In a perfect world I would love to wait and let the tension just build and have amazing, firecracker sex (actually this is exactly what I do on the first date) for many dates. But thats not the reality every time. Lets do a thought experiment:
100 girls come on a date.
A.) 20 have no affinity with you, and will not have sex regardless.
B.) 20 will not have sex on the first date, but will at a later date
if you keep meeting
C.) 20 are horny and like you, but not in any long term way. They will have sex with you on the first date, unless you don't go for it, but they won't be coming back out for another date either way.
D.) 20 like you, will have sex on the first date (and are happy to keep meeting), or will come out for a second/third date (and have sex then, if you haven't already), and by the luck of fate, don't meet anyone else and get a boyfriend before that date ends up coming about. (as in the example
@Ladylisa provided)
E.) 20 like you, but Taro at work has been putting in seven months of effort into dozen dates including Disney Land and sending two dozen pictures of cute cats. She decides that he's actually not that bad and will date him. Alternatively, she is frustrated you didn't try to have sex with her on the date, wonders if its something wrong with her, goes out to club Atom and gets picked up by Shunsuke, the bleached kari-age construction worker who fucks her in his van and 中出しs her. She has the kid and gets married. You get the idea. If you don't have sex on the first date she will end up in a relationship before your next date.
If you DONT escalate to sex on the first date vs. escalating to sex on the first date, you're losing:
C.) who are just horny and are happy to have sex to fulfill their bodily urges, but don't really care about you in particular (there are actually a lot of Japanese girls like this.. happy for a casual fling but not much longer)
AND
E.) Who like you, but if you lollygag around too long will end up dating someone else before you get around to the second date (as in the example
@john.smith provided above.
That's like 40% of the girls that you're losing by not going for sex on the first date.
If you are purposefully NOT going for sex on the first date you are wagering that the added sexual tension or whatever your goal is, is worth more than losing the girl 40% of the time. In 20% of those cases (E.), the girl might actually be your total dream girl and it's just a timing issue, but not going for sex is actually going to cost you your dream girl and potential future wife.
Some people just love wine. When they can have it, they're ecstatic and savor the 20k yen bottle to its last drop. When they can't have it they'll make do with that $5 bottle from the conbini. "Chugging terrible wine" in this analogy would be banging a fatty like ten times in a night, or keeping seeing a girl you don't really like just because she gives you sex. I agree this isn't good.
In reality its more like:
normal guy: has a bottle of wine maybe twice-three times a year. It's sometimes really excellent and sometimes really shitty, but wine is so rare that he enjoys it either way.
guy with good game: drinks wine with every meal. He samples the bad wine and the good wine, but since he samples so much he has a better idea of what actually IS good wine, so when he gets it he then calls the good wine seller to arrange weekly delivery of it to his house. After a while he has several different of his favorite, high-class wines coming to his house on different days and depending on whether he's eating fish or steak. Bon appetit!
The KEY is that you really have NO IDEA until you open the bottle of wine (have sex with the girl) how it's going to be. I've had some great, amazing dates with girls I was sure would end up being my girlfriend or at least someone regular. In the end the sex was terrible and I didn't feel like calling them back. On the other hand, I've had some flat-out boring dates with girls who had nothing to say for themselves, but in the bed they went crazy and it blew my world.
So on top of the 40% loss, you also get the girls in group B.) who are actually awful at sex and you're waiting around taking them on multiple dates when they're a brick in the sack. Why not find out that nasty little surprise quicker?
Finally..
This just plain isn't true. My friend got Chlamydia/Gonorrhea (cant remember which, but on two separate occasions) from receiving a blow job.
http://www.sfcityclinic.org/stdbasics/stdchart.asp
I would definitely avoid BBBJs. I don't get them from normal girls I pull until they become regulars or something special, and I certainly wouldn't advise getting them from a provider or any other high-risk girl. Do so at your own risk.