I think most people who really cared about it just think it's absurd that everyone has to accept planets being arbitrarily reclassified because a very small group of astronomers says so. Plenty of well-known astronomers thought so as well, and there are obvious problems with the "cleared orbit" clause, which is applied totally arbitrarily. The majority of the IAU did not even vote on the proposal, as it happened after most people had left the conference.
For example:
> Dr Alan Stern, who leads the US space agency's New Horizons mission to Pluto and did not vote in Prague, told BBC News: "It's an awful definition; it's sloppy science and it would never pass peer review - for two reasons." [...] Dr Stern pointed out that Earth, Mars, Jupiter and Neptune have also not fully cleared their orbital zones. Earth orbits with 10,000 near-Earth asteroids. Jupiter, meanwhile, is accompanied by 100,000 Trojan asteroids on its orbital path." [...] "I was not allowed to vote because I was not in a room in Prague on Thursday 24th. Of 10,000 astronomers, 4% were in that room - you can't even claim consensus." http://news.bbc.co.uk/2/hi/science/nature/5283956.stm
A better insight might be how easy it is to persuade millions of people with a small group of experts and a media campaign that a fact they'd known all their life is "false" and that anyone who disagrees is actually irrational - the Authorities have decided the issue! This is an extremely potent persuasion technique "the elites" use all the time.
I mean there's always the a the implied asterisk "per IAU definitions". Pluto hasn't actually changed or vanished. It's no less or more interesting as an object for the change.
It's not irrational to challenge the IAU definition, and there are scads of alternatives (what scientist doesn't love coming up with a new ontology?).
I think, however, it's perhaps a bit irrational to actually be upset by the change because you find it painful to update a simple fact like "there are nine planets" (with no formal mention of what planet means specifically, other than "my DK book told me so when I was 5 and by God, I loved that book") to "there are eight planets, per some group of astronomers, and actually we've increasingly discovered it's complicated what 'planet' even means and the process hasn't stopped yet". In fact, you can keep the old fact too with its own asterisk "for 60 years between Pluto's discovery and the gradual discovery of the Kuiper belt starting in the 90s, Pluto was generally considered a planet due to its then-unique status in the outer solar system, and still is for some people, including some astronomers".
And that's all for the most minor, inconsequential thing you can imagine: what a bunch of dorks call a tiny frozen rock 5 billion kilometres away, that wasn't even noticed until the 30s. It just goes to show the potential sticking power of a fact once learned, especially if you can get it in early and let it sit.
Ye the cleared path thing is strange.
However, I'd say that either both Eris and Pluto are planets or neither, so it is not too strange to reclassify "planet" to exclude them.
You could go with "9 biggest objects by volume in the sun's orbit" or something equally arbitrary.