Why does nobody give the dwarves any credit but shower the elves with all the praises about being the first civilization and the wises and blah, blah, blah.
Both cultures have clearly lost aspects of their culture. The dwarves seem like the elves to be very particular about keeping their history, but also have gaps in it. The various thaigs we've been to were part of the dwarven civilization, but had to be abandoned to darkspawn or other creatures, as they've retreated to Orzammar. In the past, the dwarves seemed to know more about the creation and control of golems - now increasingly a lost art. (Well, as our experience with the Anvil suggests, like many things in the game, one that poses moral dilemmas, too.)
Personally, I think as we find out more about Thedas' past, we'll realize its four races are increasingly connected. The elves are the most magical race and the dwarves are the ones that mine and bring lyrium ... this suggests a connection that both peoples have forgotten. There's more secrets in those thaigs.

Why do the dwarves seem to be less hated? (Not on the forums, I mean by humans in the game.)
1. They mine & have something humans actually need (lyrium). Elves have ironbark, but humans don't depend on it.
2. They're the first line of defense against the darkspawn between Blights. As long as their Legion are holding back the darkspawn in the Deep Roads, they won't emerge to the surface to bother human cities.
3. Humans don't seem to be too interested in living underground, so there's no reason to conquer dwarven 'lands' and take them from them.
Interestingly, though, just like the Elves, they appear to avoid mating with humans, mostly due to declining numbers and that such children end up 'half-dwarves'. I do find it interesting there never has been a Dwarven romance option. Oddly enough, even to a Dwarf Warden in DA:O.
Forumgoers may not like the dwarven caste system, but in reality Thedan humans don't seem to be bothered by it, after all, it's not like in their own civilizations you don't have nobility leading the high life and serfs scrounging for scraps.