If anything the last meal is an indication that we know there's something fucked about about killing this person. If we really believed they were scum and deserved to die we wouldn't worry about humane treatment or last rights we'd give the bailiff at his trial a shotgun and they'd be ready to fire as soon as they heard guilty.
Well. yeah, one thing that I was thinking was that in the past, there was a lot less process involved and individuals were mainly responsible for the death decision. Not the carrying out of the sentence, but the decision. I think if you had personal responsibility and you were right there with the individual, you might offer them a request. Not because you think it would make them feel better - but maybe to take the edge off the decision you just made...
On the other hand, now the decisions are made 10 years in advance, and the personhood of the doomed prisoner is reduced to legal briefs and filings throughout the appeals process. That's why, to me, the 'last meal' request is disingenuous to a degree. It's offered, it seems, more out of tradition than any actual human feeling toward the inmate.
Here's a thought - when a man or woman is condemned to death, the jury that came to the capital verdict with the understanding that it was a death penalty case should have to witness the execution, as must the prosecutor and judges involved in the original case and appeals. Making the death penalty more real to those involved in the process will probably work toward changing the process.