I think E-Prime fails to solve the problem, and even exacerbates it
by making people think they can avoid fuzzy thinking by playing
silly word-games with a broken language instead of doing actual work
to think and communicate more clearly.
The fact that our language evolved to give a central role to a
certain device that makes muddy thinking easier is curious (note
that "inspires curiosity" would be legal E-Prime but even more
sloppy, and "is curious to me" is illegal but clearer). Those
that created English apparently /needed/ to think muddily, and
it is /that/ which we should try to understand (I could reword
that sentence without the "is", but it would have been less
clear and no more meaningful).
I'm all for language reform--I love Lojban, I created genderless
pronouns for the Oceania Constitution, and I like to think I take
some care to use my native tongue effectively. I'm all for
introducing people to ideas like E-Prime, but let's not rely on
it as a substitute for actual rational thinking.