Alzrius said:
A lot of this, however, was repealed at the end of 2E, or in 3E. For example, Faces of Evil mentions that there are no half-baatezu, but it was only a short while later that half-devils (remember, in 2E "devil" was another word for "baatezu") were premiered in the Guide to Hell. Likewise, we know the half-fiend template in 3E can be the result of any evil outsiders. And even PS said there were baatezu-descended tieflings, which meant baatezu had some form of sexual reproduction.
There wasn't really anything to repeal though:
Actually as I recall, 'Faces of Evil' didn't say that Baatezu couldn't sexually reproduce, just that they couldn't sexually reproduce with each other. Female Baatezu are sterile. Male Baatezu could still mate with mortals. And this didn't apply to unique Baatezu such as dukes, Lords of the 9, any other sort of noble baatezu, etc. GtH just formally talked about half-baatezu, but it didn't really overwrite anything. It's been since overwritten in many ways really more than it revoked anything from Planescape, but that's verging off topic.
Yugoloths could also mate with mortals, though there was never any sort of convention dealing with the results of the pairings. At least one character, Kylie the Tout, was rumored to be only a generation seperate from a yugoloth. Yugoloths looked down on sexual reproduction amongst themselves as crude, and at least greater 'loths born of the matings were relegated to 2nd class status amongst their kind since they were born into caste rather than having clawed their way up from mezzoloth, and gone through all of the literal and metaphorical purification along the way.
Tanar'ri would just mate at the drop of a hat with darn near anything, so no surprise that you had a lot of half Tanar'ri subtypes running around the planes.
Honestly though, I think that in 3e there's been an obvious slant by WotC in favoring the good/evil axis, rather than the law/chaos axis. Good and evil has been more exposed, more used, and been given more options, rather than the same for law/xaos. Just the interest of the current writers I imagine, or perhaps they feel that good/evil appeals better to their target audience. I can't really say. Law/Xaos seems to me to have been more heavily visible during the Gygax years, and then also perhaps at its height during the Planescape years. We've yet to have the same law/chaos dichotomy so well expressed and given note in current material, and honestly I'm not holding my breath. Remember, a good DM can overcome a lack of official material (for whatever reason such material isn't being published, but that's another thread).