Well, I agree with some of your points. Every author has some specific styles and writing charactristics like you mentioned that most of her heros belong to extra rich familes and her heroins are poor but egoistic. BUT she is still the favorite writer of so many people. WHY? because she is different anyway. If she's specific in the selection of her chracters then she often comes up with the subject that revovle around our lives unlike the other typical female writers. For example, when I read her Peer-e-Kaamil, Haasil, Laahaashil and Man-o-Salwa then I got to know many realities about the relationship between God and Man. I analysed myself that who I am and What I am. Also she tries her best to depict human thoughts and psychology in many of her creations. The fond of reading typical romantic novels cannot digust her novels and I admit that.
Besides, the philosophy and the diction she uses is remarkable and I think that is the important thing that a good author should possess. Above all I think some readers read books NOT to get their lives influenced by the writings but just for the sake of fun , relaxation and enjoyment, it doesn't matter for them if the novel is not based on real life facts. So even if the people do not really concernd about the reality based thiongs n novels they do read Umaira Ahmed.
Apparently, Umaira's first story doesn't have anything impressive and she herself admitted in the preface that it was her weakest creation ever. But it always depends on the reader that how he grabs anything which is inspiring for him/her because author never explains anything.