The separation of powers was essential to prevent the consolidation of government and the formation of centralized, authoritarian tyranny to which all governments are prone. Jefferson has often been referred to as a proponent of "States Rights," but his main interest was not so much in the rights of States in and of themselves, but rather in a division of powers in order to prevent the destruction of liberty that would inevitably result from a national government that gathered all powers unto itself. So much for government run health care!!! From one of the authors and signitors of our constitution. I suppose you will have to argue with him as well.
Consolidation Destroys Liberty::
"What has destroyed liberty and the rights of man in every government which has ever existed under the sun? The generalizing and concentrating all cares and powers into one body, no matter whether of the autocrats of Russia or France, or of the aristocrats of a Venetian Senate. And I do believe that if the Almighty has not decreed that man shall never be free (and it is blasphemy to believe it), that the secret will be found to be in the making himself the depository of the powers respecting himself, so far as he is competent to them, and delegating only what is beyond his competence by a synthetical process, to higher and higher orders of functionaries, so as to trust fewer and fewer powers in proportion as the trustees become more and more oligarchical." --Thomas Jefferson to Joseph C. Cabell, 1816.
"When all government, domestic and foreign, in little as in great things, shall be drawn to Washington as the center of all power, it will render powerless the checks provided of one government on another and will become as venal and oppressive as the government from which we separated." --Thomas Jefferson to Charles Hammond, 1821.
"The greatest [calamity] which could befall [us would be] submission to a government of unlimited powers." --Thomas Jefferson: Declaration and Protest of Virginia, 1825.
Further on Consolidation Leads to Corruption:
"I wish... to see maintained that wholesome distribution of powers established by the Constitution for the limitation of both [the State and General governments], and never to see all offices transferred to Washington where, further withdrawn from the eyes of the people, they may more secretly be bought and sold as at market." --Thomas Jefferson to William Johnson, 1823.
"Our government is now taking so steady a course as to show by what road it will pass to destruction; to wit: by consolidation first and then corruption, its necessary consequence. The engine of consolidation will be the Federal judiciary; the two other branches the corrupting and corrupted instruments." --Thomas Jefferson to Nathaniel Macon, 1821.
Consolidation Usurps the Rights of States:
"Monarchy, to be sure, is now defeated,... yet the spirit is not done away. The same party takes now what they deem the next best ground, the consolidation of the government; the giving to the federal member of the government, by unlimited constructions of the Constitution, a control over all the functions of the States, and the concentration of all power ultimately at Washington." --Thomas Jefferson to William Short, 1825.
"I see,... and with the deepest affliction, the rapid strides with which the federal branch of our government is advancing towards the usurpation of all the rights reserved to the States, and the consolidation in itself of all powers, foreign and domestic; and that, too, by constructions which, if legitimate, leave no limits to their power... It is but too evident that the three ruling branches of [the Federal government] are in combination to strip their colleagues, the State authorities, of the powers reserved by them, and to exercise themselves all functions foreign and domestic." --Thomas Jefferson to William Branch Giles, 1825.
"[We] believe that to take from the States all the powers of self-government and transfer them to a general and consolidated government without regard to the special delegations and reservations solemnly agreed to in [the Federal] compact, is not for the peace, happiness or prosperity of these States." --Thomas Jefferson: Draft Kentucky Resolutions, 1798.