Clearly you have to pick one variant and stick with it. I assume it would be the lowest common denominator, so SAE for North America and R.P. for Britain. Devising a new orthography for each dialectal group would be impractical.
In my language, we have "spisovná ceština" as the standard. You can of course pronounce it weirdly if you insist on sticking with your local accent, but everybody is capable of reading it with the right pronunciation, it's almost fully phonetic, and it serves as an anchor for the language as a whole (so I can tell the Bohemians to frak off when they mangle it). Now, Czech is of course a very small language with some 10-11 million speakers. It naturally evolves towards greater homogeneousness. English is now the global lingua franca, and different accents/dialects are already undermining this role. It seems to me that having a pronunciation standard 'embedded' in the orthography would help protect it from diverging too much.
But then again, I don't care that much, it's not my native language.
p?n?nsjul?
b?tn
There are many ways of pronouncing English, we all get it. Not that I don't find what you're saying informative and pretty interesting, but it's kind of besides the point.
See above. English speakers need to get over their exceptionalism complex. It's a language like any other, and it should strive to achieve at least some degree of standardization, especially if it's supposed to serve as the global language of choice for the foreseeable future. Having a spelling-pronunciation disconnect of this magnitude is a recipe for future misunderstanding. That's just my humble opinion as a non-native speaker.
Yeah good luck coming up with a standard which reflects New Zealand, Irish, South African, Australian, Canadian etc Englishes too. You're simply never going to get the vowels to match, or stress and schwas, much less a common treatment of the rhotic. Improvements could be made to things like silent letters, but that's about it.