But if I need an abstraction to talk to my database, why not choose a database that requires no abstraction?

I've used ORMs and I've had to write my own once or twice, I really don't like them.

Surely any time you have a data store that can work with multiple programming languages and platforms you're going to end up with an abstraction layer because of different programming languages' data representation?

Even for things as simple as integers, do you have unlimited precision, unsigned value support and null values?