NASA distinguishes four types of exoplanets: Gas Giant, Super-Earth, Neptune-like, and Terrestrial. The question asks why ice planets termed "Neptune-like" and not "Uranus-like".
Let's start with some statistics: What is curious, that (at least according to scholar.google.com
), intially more icy exoplanets were termed Uranus like planet
rather than Neptune like planet
before eventually, the latter term started growing:
1980 to 1990
- 2 citations with
Uranus like planet
between 1980 and 1990 - 0 citations with
Neptune like planet
between 1980 and 1990
1990 to 1995
- 3 citations with
Uranus like planet
between 1990 and 1995 - 5 citations with
Neptune like planet
between 1990 and 1995
1995 to 2000
- 2 citations with
Uranus like planet
between 1995 and 2000 - 4 citations with
Neptune like planet
between 1995 and 2000
2000 to 2005
- 4 citations with
Uranus like planet
between 2000 and 2005 - 12 citations with
Neptune like planet
between 2000 and 2005
2005 to 2010
- 4 citations with
Uranus like planet
between 2005 and 2010 - 43 citations with
Neptune like planet
between 2005 and 2010
This supports the hypothesis that it was a "vote with the feet", rather than something coordinated, much like initial density fluctuations in a protoplanetary disk which might serve as the seed for a planet, or not.
@uhoh already suspected this in a comment, plus also mentions that the pronouncaction of Uranus might lead to unintended puns when talking about "planets like ...". It is sometimes these linguistic pecularities which make a brand successful and another one not.
I'm 100% sure that
- it's because of the way Uranus sounds when said out loud, and
- the decision was made in the collective unconscious, we'll never find a smoking gun, or a...
After all, there quite some similarities between Uranus and Neptune, see e.g. the concise comparison between the two planets at WolframAlpha, although there is also reasoning Why Neptune and Uranus are different.