From the very interesting link just provided:
Housing conditions were deplorable. Overcrowding was a serious problem, and bred disease and infection. Malnutrition was common. The death rate in Dublin (27.6 per 1000) was bad as Calcutta, and the city’s slums were amongst the worst in the world. Over 20,000 families lived in one-room dwellings. There were often more than ten families in town houses that were built for one upper-class family in the eighteenth and nineteenth centuries. These houses became dilapidated when wealthy elites left them and moved to the suburbs. The houses were often taken over by landlords who rented them out, room by room, to poor families, and they quickly became slums. There was little privacy. Facilities for cooking, cleaning, and washing were wholly inadequate. Sanitary conditions were worse. Many tenement buildings shared one lavatory in a yard.
I'm really surprised and disappointed that you think this type of treatment of tenants is justifiable in the context of the "norms" of the time, "everyone else was doing it, so why not me" does not seem to me to be the right way to treat people, or perhaps I'm picking you up wrong.