Nice initial post but it leaves a lot out.

1) Those charts/tables for haste assume no dual wield/martial arts which is nice for comparison, but really underestimates the majority of the population. AKA a thf/nin isnt really going from 24 to 25%, they are going from 44 to 45 (made up for example)

2) 80% haste isnt a 400% increase in attack rounds, at 240 dly you have 15 /min, with 80% haste you have 75. Thats a 500% increase. You had the right calculation when you translated it to hits.

The TLDNR version:
Haste at smaller values is pretty crap and you might not notice 22 to 23 % haste. Add on bard songs, whm, and dualwield/martial arts and going from 79 to 80% haste is huge.