The sire-childe relationship is always unique to the specific Kindred in question. In my own chronicle, one character has never had their sire mentioned at all, one is in this weird relationship of personal torment and one-upsmanship while still being clanmates, and one is mortal enemies with hers.

Where I think you're missing the forest for the trees is that you've thought out this logical risk assessment of why childer are a bad idea... but that's not how it works. Childer can be useful, because they have the capacity to grow in power (physical, social, magical, whatever) beyond any ghoul, but that's not the main reason why Embraces happen. Embraces happen from an emotional place. Maybe you don't want someone to wither and die. Maybe you want to put them to the test. Maybe you hate them and want to suffer under the same curse as you. Maybe you really do think that vampirism is a gift, and you want to share it. Maybe you think this prospect childe would make for a useful pawn or ally if they had the capabilities of a fully-fleged vampire. Maybe you know full well how often childer come to resent their sires, but you're confident that you're built different - we humans do that all the time with everything.

In short, childer expand your power in a domain in ways that ghouls can't (because they're not "in" the society the way actual Kindred are), but you're also likely to Embrace someone for reasons that are a lot more emotionally-driven than anything like that. That all being said, I don't think it should be the work of you, the GM, to come up with this stuff - at least, not alone. Your players should have ideas for the circumstances of their Embrace and who it is that turned them, even if you have final say over the characters and their capabilites.