Why might it be a problem that there are $435$ members of the US House?

Compared to most other representative democracies in the world, $435$ is a very large number, which makes the House difficult to organize.

$435$ members of the House, plus their staff, is simply way too many people to fit comfortably in the Capitol Building.

Compared to the total number of US citizens, $435$ is a relatively small number, which means that each member of the House is representing an average of more than $700,000$ citizens. This could make it harder to members of the House to have a close relationship with their constituents.

None of these.