Spanish is largely written as it's spoken. Even with its many accents and dialects, holding a spelling bee would be ridiculous because of how easy it is to deduct writing from pronunciation.
That being said, if it was reformed to the point where it absolutely was written as spoken, it would become very ugly.
So if you can get objective and think about 150-300 years in the future , do you think there will be no changes to cleanup things in the language ?
You can change it and clean it up all you like but that won't stop its evolution and a hundred years later the spelling and pronunciation will be out of sync again.
I don't mean that we should necessarily avoid reform but what you get when you do a serious reform is a new language that is different from all the dialects and it must either be imposed from above or be in some way sufficiently attractive for people to adopt it. And then you have another dialect.
See also the xkcd joke on standards, I think it applies here too: https://xkcd.com/927/
I guess what I'm saying is maybe they should take a swing at making something similar to esperanto, but with a focus on making it as understandable by an english speaker as possible.
I don't think you can generalize the US pronunciation this way. Source: This was my grandfather's name.
The point is that there are many ways to pronounce the same word even within one country.
If you write how you speak I will not be able read what you write and vice versa. English has a wide range of dialects, nare you going to try to impose on on the rest of us. Someone like me used to broad West Country speech would spell rather differently than a Glaswegian for instance. Should we have diacritics to indicate stress? If so will you choose the common US (stress the ultimate syllable) or British practice (stress the ante-penultimate syllable)? In British English, the name Bernard is pronounced with the final vowel as an unstressed, almost elided, obscure vowel; but it is a stressed long a in US English.
I often see people demanding that English be written phonetically. Many of those people seem to be unaware that their own languages also have dialects and that they would be equally unable to write phonetically in a way that would satisfy all users of that language.
There have been numerous attempts at consistent auxiliary languages. None have become very popular. The only 'widely' used auxiliary is Esperanto and that has already shown itself to be subject to all the same evolutionary forces that drive changes in natural languages; people must invent new words and then they disagree about how to spell them, how to use them, what gender they must have; slang is created and eventually becomes normalized in some communities but not in others, etc.