Does Riot not take feedback from the test realm anymore???

Playtest is a separate group internal to riot that does try to get a feel for that stuff, but they're still a relatively small group with time for only so many games before it hits live. It's also more overall design stuff they're looking for, rather than precise numerical balance as far as I can tell, since numbers are easy to tweak the following patch, but if a design mechanic doesn't feel right at all that's a harder problem to fix.

I also don't think duskblade is quite as far out of line as you're making it out to be. It's out of line yes, which is why it was hotfixed and has further nerfs coming next patch, but the game is far from unplayable.