I realise you live with a designwr but you must realise that the first-hand knowledge you have can't be generalized. I know professional designers (both corporate and freelance) who use a floss workflow. Inkscape in particular is quite poweful and has some features that illustrator doesn't.
I also know of designers who swear they need to run their adobe suite on a mac, but thats not the point. Professional designers (as in geting paid for their work) can, and do, use some of the floss tools.