Well, the issue is that a lot of effort goes into these characters. A lot more than, say... an MMORPG toon, who gets to resurrect/respawn after death. There's really no reason to argue against capture RP. But, death is a touchy subject, especially when so many people in the past have used OOC motivations or metagaming to kill a person's character, which waters down the gravity and seriousness of the situation. Not everyone can be trusted to be a quality roleplayer. Some are just assholes that will use kill rules to harass someone over and over - so, what do you do about it then? Even if the gameplay rules are being followed, the motivations are skewed, and putting rules on motivations is something I'm sure everyone wants to avoid.
So, in this sense, it's more than one-sided meter-resetting or someone saying they just won't accept the death. To look at only the victim's side of things and their reactions in this argument is to blind ourselves to the multitude of other possible factors that need to be calculated into the situation.
In essence, we are writing interactive books and we all want to be the heroes of our own stories. And we all have the right to be when it comes to roleplay. That's a core rule written into every RPG tabletop book on the first few pages. "The players are the heroes."
The issue with roleplaying Gor and death in Gor is that death is final. There's no magical or supernatural way to bring people back, unless you want to clone them like they do in the Nest, which opens a whole other can of worms that sparks another debate over what kind of tech is accepted, etc.
However, to finally answer your question - yes, it does water it down and it renders the caste of Assassins pointless and useless when it comes to player interaction. Instead of going somewhere and killing someone and having that kill honored, the Assassin more or less has to capture the person, hope that person honors the capture, drag them somewhere that they cannot debate the kill rules, kill them, hope the person honors the kill, and hope that people don't metagame finding who did the kill, etc, and retaliating. That's a lot riding on hope of the other player's honor, but it's also a lot riding on the quality of the roleplay when looking at it from the victim's point of view.
And then there's the old debate of whether or not the meter should come into play with such kinds of stories since a quality roleplayer doesn't necessary have the machine power or the click-skills to perform their duty as well as some hardcore gamer with a great machine with less-than-desirable roleplay skills.
It's just too much to factor in for a global decision.