This concern perplexes me. There's a long history of residents in states having uneven numbers of U.S. House representatives - over time, there probably have been nearly as many Congresses where this was true as untrue, and it was true as recently as the 1960s when Hawaii and New Mexico had at-large representatives. We also commonly see residents in states having uneven numbers of state representatives - including my home state of Maryland, where many people have three representatives in the state house of delegates, but others have one or two. Are these critics, including Sensenbrenner, developing a new "right" to equal number of representatives that has never existed before?
Our website has some useful materials on the history of multi-seat districts for the U.S. House. See, for example: