No, being married to a Prince does not make you a princess. That would be logically consistent and that's what I originally thought too, by mistake. Kate Middleton was given a title, Duchess of Cambridge, but she is no "Lady" because she is not of royal blood. I'm not the one who talks like this, confers these silly salutations like this. Lords and Ladies don't mean fiddlesticks to me. I think the idea of nobility is crass and stupid, but don't tell me rubbish that it doesn't exist. You might not agree with it; but denying reality if it doesn't fit your opinion doesn't seem very smart.
I don't there is an effort to deny that the royal bloodline exists. Rather, I think there is denial that royal blood somehow makes one person more 'noble' than another. As it was stated in a previous post, the progenitors were just as human as the rest of us.