First principles:
1) Desirable societies are ones where everyone has equal dignity. That is desirable not just for the lower classes, but also for the upper classes, because even the wealthy should feel ashamed interacting with another person other than as equals.
2) Equal dignity is hard to define precisely, but its component parts include economic opportunity and social stature. People have equal dignity, notwithstanding an employer-employee relationship, when, among other things: a) the work is a choice, not a consequence of desperation; b) when the interactions between people are not defined by their work; and c) when nobody internalizes the feeling that someone is better than them, or that they are better than someone else because of their work, education, upbringing, or social class.
Domestic servitude has a unique capacity to create unequal dignity because: a) it's often undertaken because someone has no better opportunities; b) because of the unique master/servant relationship that arises out of one human purchasing the services of another in his individual capacity (rather than, e.g. both of them working for a larger organization); and c) because working with the sole purpose of making another human comfortable has a unique way of cementing pre-existing economic, education, or social divides.
I do not know anything about India besides what I've read. But in Bangladesh, there is a deeply ingrained class structure. The domestic servant does not think himself the equal of his employer, and employers usually don't think of servants as their equals.
In first world countries domestic service suffers from these problems less because people have alternatives and so human labor is very expensive. Plus, the culture is just better. People in small town Iowa don't think that venture capitalists in San Francisco are better than them, and it would be an egregious social violation for the venture capitalists to think so out loud. None of that is true in Bangladesh, where social interactions are strongly dictated by one's class, work, and education, with domestic servants being near the bottom of the pile.