I think that that just means that there's not much point in developing them further. they're still great for the simple tasks, like texting while driving.

I mean, that only says something about the money making part and not the pure usability. For many people the commercial options are a gimmick, sure. But are these options, with a clear focus on milking the customers for money, really the ultimate state for voice assistants? I'd argue they are not. There is a space for free voice assistants that let users control their data and that still provide a value. Beyond users with disabilities that make it hard to impossible to use computers, voice assistants won't ever do something you cannot do with a computer (which includes smartphones). If that makes you consider them a gimmick then I don't have an argument. But I think it is nice and convenient to be able to use a computer with your voice while doing something else.