Uranium was named after the planet Uranus in 1789, and the planet had only been discovered in 1781. So it wasn't part of any tradition of naming — it was a chemist who decided, on his own volition, to name a new element after a new planet. It would be nice to see Klaproth's original article to see if it explained anything about the name, but it appears to be quite difficult to get one's hands on (it is not scanned on the internet from what I can see); I have found the suggestion that Klaproth was impressed by the publicity given to the discovery that Uranus had two moons, and maybe was trying to attach some of that to his own work. Today it would be tempting to suggest that just as Uranus was then the furthest-known planet from the Sun, and Uranium is the heaviest element on the periodic table that occurs in large quantities naturally, that this was the analogy Klaproth had in mind, but given that the first periodic table was not put together until a century after his discovery, that may be ahistorical. (Without Klaproth's article, it is hard to say what exactly he knew about its properties.)

Anyway, the naming of elements is pretty capricious. It is of note that two elements before uranium is thorium, named after the Norse god Thor, but this was discovered and named long after uranium was named (so if they had wanted, they could have called it jupertium, but they didn't). In between the two is protactinium, which was initially called brevium (for its short half-life), but then given a much less literary name to honor its being the parent of actinium in the uranium decay series. There is, in other words, no real rhyme or reason to many element names.

Neptunium and plutonium were so named to extend the planet metaphor outwards. Obviously other names could have been chosen. It is amusing that the abbreviation of plutonium was chosen by its discoverer, Glenn Seaborg, as "Pu" and not "Pl" because he wanted to make a somewhat juvenile joke (plutonium is toxic — "pee-yuu" in English is an expression for something disgusting; Seaborg was surprised nobody challenged him or picked up on this). Pluto, the planet, is also conveniently named after the god of the underworld, and plutonium was discovered in the process of researching the first atomic bombs.

Anyway, if you are saying, this seems arbitrary, yes, it is.