Accessibility and a single chassis that does the vast majority of things. Even if they're never as fully dexterous as the average human (doubt it) they're still as dexterous as a somewhat handicapped human, which is already clearly enough to function decently in most of society and is far from useless.

If you want several bots all custom built to specific tasks, go for it. That will happen too. But a generalist has value of its own.

> imagine if your roomba had legs

That would probably be an improvement. Floors are designed for people, and may have several levels. An ideal vacuum would probably look something like a centipede.

Anyway, the appeal would be that it can perform several tasks. It doesn't need to perform all the tasks a human can to fulfill that.