I think Lexus need to do better in this regard, however the guys at Viastech do great working adding these things to Lexus' with second generation and later audio systems.
They just aren't interested in supporting earlier cars, hence i'm having to do it myself....
Unfortunately its a bit of a timing thing.
From about when the New IS was released, a lot of standard Toyota/Lexus cars all come with AUX in, many with MP3 (e.g. new Prius, Yaris, IS).
The new GS was, well, too new! lol