To me, the radiant quests are just something to continue on with the guilds. That's something that annoys me about Oblivion - I become Arch-Mage of the Mage's guild and thats it, game over, no quests left. Skyrim makes up with that - you have the 'aftershock' to deal with, but it's only started if you ask Tolfdir about it. In the Thieves Guild you have the jobs to do. In the Dark Brotherhood you have the radiant contracts. They're not meant to be compared to 'proper' quests, but they give you something to do every once in a while.
Besides, they're completely optional. If you don't like them, then just don't do them!
I think radiant quests are somewhat fine. They could have some depth in them, but other than that they are alright.
The problem with quests in general is that everything is frontloaded to you. You reach the best stories in the game immediately and then after those are done, you're left with exactly that feeling of doing randomized content that contributes into nothing and rewards nothing.
So to fix the problems with radiants, they need to look at fixing the supporting gameplay structures like economy, character progression and pacing (not frontloading the best stories and rewards to you immediately, but gradually over time depending on some arbitary alignment/reputation system.)