No we've seen a great degradation of it since Lincoln and especially since FDR. Don't get me wrong I don't blame it all on the executive branch, all three branches have done their share in fact the courts bear the majority of the responsibility because of their complicity and taking unto themselves the power to interpret the Constitution instead of just going by what it actually says.
You may feel the Constitution's original purpose has degraded, or eroded, since Lincoln and FDR...but at the same time...this country saw it's best days between 1900-2000, during all of that degradation.
The 13th Amendment dos not represent degradation, IMO, but the Volstead Act was a failure.
I think the notion that the Constitution has degraded since the founding fathers authored it, is largely a tool used by the GOP to bolster the resolve of it's strongest demographic, the southern evangelical social conservative base.
That strategy attempts to assuage the commonly accepted idea that the South is evil because, they were pro slavery in the 1800's. A culturally accepted perception, reinforced by the 60's Liberal revolution, is that southern Evangelical social conservatives are racists. Just look at Hollywood movies like Mississippi Burning, Easy Rider, Deliverance, and so on.
The danger in that philosophy is that the converse never happened. We don't have an example of what would have happened if the Constitution remained unaltered from 1790 on, nor do we have an example of what the south would be like if the Civil War never happened. It's easy to picture a Utopian version of what would have happened if we remained a Jeffersonian agricultural nation with a scholarly ruling class.
Our country has gone through eras where one of the three branches has essentially gained disproportionate influence. The latest shift to the executive started under George W Bush, and Obama has continued that.
If the outcome of any political platform results in the idea that the other guys are 100% wrong, and what would have happened is 100% right, if only you were in charge...you are the victim of the political version of "back seat driving"
As for changes to the Constitution, I'd like to see an Amendment prohibiting laws that ban gay marriage. I'm a voter, and will vote for politicians that would appoint SCOTUS Justices that would be more likely to support that.