I don't care about other women making themselves 'beautiful', but I do care about the reasons behind it and also the ways in which they do it.
If somebody used foundation which changed the colour of their skin, thereby evening it out and they felt happier as a result, great. I've used a concealer to cover up spots or dark under-eye circles.
If they're using chemicals which adversely affect health, then I think it's an issue (I agree with MrsDV about lighteners and sunbeds, though I'd point out that sunbeds are also used for health reasons for psoriasis sufferers, whereas I'm not sure lighteners have any positives).
If they're doing it for reasons of low self-esteem (and you could argue that this applies equally to women tangoing themselves - frankly nobody looks better bright orange, so you must have psychological issues to do it), that's a feminist issue.
If they're doing it for reasons of low self-esteem related to race, then it's also an issue, but possibly more so (cultural, probably feminist too).
But then, I speak as someone who was given three(!) make-up bags for Christmas but who owns only one concealer as the sole make-up item to put in them. Not because I am supremely happy with my own appearance but because a) I don't give enough of a shit about what others think, and b) I'm fundamentally lazy and don't want to get out of bed any earlier... Which brings me back to psychological issues being a societal problem.