Everyone’s situation is different. But typically the reason this offends is because for a stay at home mom a vacuum is a work tool. If the current vacuum is broken then you should just get a new one. It shouldn’t take the place of a Christmas present, which is the opportunity to get her something related to her personal interests rather than her job.
Interesting point of view. But it's common for a man to get a work tool as present (e.g. a drill or a set of wrenches), with the obvious implication that the man will usually be the one who will have to use that tool to fix things around the house - and I have never seen anyone find that offensive. So what makes the vacuum cleaner different?