I was reading the Anti-Federalist Papers (a fascinating discussion, in document form, about the strengths and weaknesses of the Constitution), and in Section 23 Brutus 3 they make a number of good points. They note that a fixed number of representatives per state in the Senate is nonsense, especially since the powers of the Senate are so immense; also that the amount of representatives in the Assembly (i.e. House of Representatives) is sorely insufficient (even at that time, when population was MUCH lower) to represent a country as large and diverse as the United States. Furthermore, they mention that this dynamic makes the system likely to produce an elite aristocracy... who will in short order control the whole thing.
Note: They did not even know that later the U.S. would pass the Permanent Apportionment Act which locks the number of representatives at 435.
Think about that, the founders said there should be one representative for each 30,000 citizens (which was only half the representation the English at that time enjoyed)... we are now at over 767,000 citizens per house representative, and the Senate grows ever more powerful. We were warned all the way back BEFORE the Constitution was even made law, that UNDER-REPRESENTATION and CORRUPT ARISTOCRACY would likely be outcomes... nothing was done... in fact laws to WORSEN the problem were enacted.
We now exist in a state where under-representation is codified and worsens every year... and wealthy elites can easily buy the few "representatives" allowed to exist. This cannot be allowed to continue, we MUST AMEND THIS.
"They should be satisfied that those who represent them are men of integrity, who will pursue the good of the community with fidelity; and will not be turned aside from their duty by private interest, or corrupted by undue influence; and that they will have such a zeal for the good of those whom they represent, as to excite them to be diligent in their service; but it is impossible the people of the United States should have sufficient knowledge of their representatives, when the numbers are so few, to acquire any rational satisfaction on either of these points. The people of this state will have very little acquaintance with those who may be chosen to represent them; a great part of them will, probably, not know the characters of their own members, much less that of a majority of those who will compose the foederal assembly; they will consist of men, whose names they have never heard, and whose talents and regard for the public good, they are total strangers to; and they will have no persons so immediately of their choice so near them, of their neighbours and of their own rank in life, that they can feel themselves secure in trusting their interests in their hands."
-Brutus IV