I used to have to visit Hawaii every year from London and it was easily the worst trip I had to make ina job that took me to every continent -some quite often.
There is very little business travel most of the time and as pointed out earlier why go half way around the world to go to what is essentially a Caribbean island in the Pacific-Honolulu is not that great either with the usual US disregard for form and style in construction .
The reason why it was so bad was the US transit which had to be judged carefully to avoid missing your connection but also avoid spending 5 hours at SFO or LAX. Coming back was even worse because the transit times were so awkward- the only civilised route was via YVR . The awful slog of the flight coupled with arriving in Hawaii always at close to midnight local but around 1000 Euro time means a first night sleep is impossible and so jet lag pretty much guaranteed
Back to your point about a non stop it is doable now with the A340 A380 and definitely the 777 esp the LR version but it is along way and a daily flight would be a big commitment needing a full 'heavy ' flight deck crew and more than a 24 hour layover so an expensive proposition from the crewing point of view.
To give you an idea about why it hasn't been tried is that as far as I know there are no or very few non stops from the big US east Coast metro areas like NY and DC they mostly make you change planes at a hub further west.
I hope your health problem improves
PB