I know a couple of people who consistently say “brought” when they mean bought. This despite a lifetime of having heard the correct word used. This mistake, although not common, is sometimes heard around the London area – I haven’t heard it anywhere else. This causes me to stumble mentally every time I hear it as does the word nuclear pronounced as nucular. What happens is that for a time I am distracted from the message by the pronunciation. Others here obviously also find that to be the case.
So what we have is the most powerful man in the world's most powerful country trying to give us what he sees as a powerful message, but a good many of his listeners are being distracted from the message by his speech mannerisms! That has to be undesirable. Those of his listeners who themselves say "nucular" would not be upset or think any the less of him were he to pronounce the word properly, so the effect is all negative for him.
Certainly language is all about communication and it changes and develops with common usage, but that can only be through a popular trend (carefully avoids using "slippery slope"!). Whether a pronunciation or usage has become “accepted” can only be assessed by a body that is generally recognised as suitably qualified, and to see what is accepted right now one would, at least I would, refer to a number of well-known dictionaries. They will not suggest the use of brought for bought or nucular as a way to pronounce nuclear because right now those are not accepted.
So lets resist the trends that we find unpalatable or ugly to try to prevent them from becoming accepted!
dxb.
