First, a bigger House would diminish the impact of malapportionment that comes with single-member states. A certain amount of malapportionment is inherent in House redistricting, but as the number of single-member states grows, this effect becomes more and more pronounced. The largest single-member state, Montana, requires a representative to take on over 1 million constituents. On the other hand, the smallest state, Wyoming, only has 582,000 constituents.
This will become more pressing in 2020, when Rhode Island is expected to lose one of its two House seats. Unless Montana gains one back, there will be more single-member states than at any time in our country’s history. Roughly one in six states will be single member; the only time that ratio was higher was immediately following the 1820 apportionment, and then only because three single-member states had been admitted to the Union shortly before the reapportionment.
As a side note, and as a result of the next apportionment after the 2020 census, New Jersey will likely have its smallest congressional delegation since the first decade of the 1900s, New York since the first decade of the 1800s, Ohio since the 1820s and Pennsylvania since the 1790s. As a result of the last apportionment, Illinois has its smallest delegation since the 1860s, Indiana since the 1830s, Iowa and Missouri since the 1850s and Massachusetts since the original apportionment. This is all despite massive increases in population size.