I think those are both good points. At the end of the day every death in a novel is planned. The aim has to be to write something that is satisfactory as a book, not as a depiction of real life. Even the meaningless deaths have meaning in the book, if they serve to surprise the reader, make him think or achieve a similar effect.
It's also worth remembering that even if you
do stick random meaningless things into your story, your readers will assume they have meaning, and will come up with their own explanation.
It's funny that someone mentioned
Lost and the polar bears, because that's a perfect example that I used in a blog I wrote on this topic. The makers of
Lost have outright stated that the polar bears had no symbolism or significance whatsoever, but many fans continue to reject this, and postulate about what they might mean.
When writing a book or any story, you're not faithfully recounting reality. Every single thing you write, you're
choosing to include, and every single thing you leave out, you're
choosing to exclude.
As readers increasingly expect tight, fast-paced stories trimmed of all fluff, readers increasingly presume anything you've included is there for a good reason.
That's not to say you should explain or justify everything you include, but it's worth being aware that readers will try explain things themselves, and if they get frustrated at their inability to come up with an explanation for something (such as the polar bears in
Lost) you run the real risk of losing your audience.
An example that springs to mind is Jon Snow's parentage in
A Song of Ice and Fire. This is probably one of the most discussed "mysteries" of the series, and a big part of why many people keep reading it. As it stands, unexplained, it's a marvelous tool for dragging readers into the story.
However, imagine for a moment that Martin concludes the series, and Jon Snow's parentage is never revealed, and is not really particularly important to the final climax at all. It is revealed it's a total non-event - a completely random, unimportant, unanswered question.
I suspect the outrage, the sense of betrayal many readers would feel, would be staggering.