Destriarch, I understand where you're coming from. I just tend to find rolls a bit necessary, more along the lines that Zomben says.
However I do agree that it can increase the load on the GM who has less guidelines for deciding when to roll/not roll and how to roll. And equally, if the GM gets it wrong it can be difficult for the players.
Since you asked for more info about skill system, here is an excerpt from my review of DW (which tries to go into a bit more detail about the system, but needs a bit more polish before I publish it)
Each profession has access to certain skills - some of which are shared between more than one profession. However it is not a "true" skill system in the sense of RuneQuest for example, as:- skill acquisition is not on a consistent basis - it comes in fits and starts as different professions increase in rank
- there is no standard mechanic for applying skills - each comes with its own "mini-rules"
The professions certainly allow for a little overlap in terms of equipment they can use, combat, magic and other skills, but there is no multi-classing. This does help really differentiate the professions and make for a variety of different responses to a situation given the makeup of the team.