Tolkien could also be showing the natraul vanity of the Tooks.
Instead of being buried in the shire, like normal, well-to-do hobbits, Merry and Piippin decided to go out with a "bang".
Being buried next to the son of Isildur is a pretty big bang to go out with.
Not the most plausible definition in literary terms, but it is another view on the topic.
