Breandán wrote:
I don't know how this relates to the linguistic side of things, but it is always funny to hear people advocating the "recorder" as a "simple" instrument when the tin whistle is a _much_ simpler instrument to learn to play - and far superior, especially if you are aiming to play Irish music.

I'd say that just makes the analogy all the more accurate. Esperanto isn't the easiest language on the planet -- it's got its own bizarre quirks because it was devised by a guy who didn't know all that much about language in a time when even linguistics experts didn't know all that much about language.
The longevity of the recorder in schools is more to do with it being perceived as an easy instrument than it actually being one. (The whistle is unarguably easier, and the harmonica and glockenspiel are debatably easier too.) They also say it's good because it's cheap, but again this is perception rather than reality. (The whistle is definitely cheaper to make -- cheap recorders are only cheaper due to scale, and bottom-end harmonicas are on a par with school recorders.)
One of the main reasons Esperanto seems easy to learn is because it was invented with the teaching techniques of the day in mind, and that means it's particularly easy to teach using 19th century teaching techniques.
The reason language is in such a dire state in schools is that we keep forgetting the lessons we've learned and reverting to earlier techniques, and there's a risk that Esperanto could actual damage teaching due to circular logic:
Esperanto was designed to be taught a certain way, therefore it can be learned very successfully that way, which then leads the teacher to assume that the teaching method is effective in and of itself, with the end result that they try to teach other languages in a manner that is simply not effective for natural languages.