I disagree.
As did they not have to prove it was not gambling, and it took a while so if it took a while it was hard to prove.
What makes it not gambling is MU and the ability to change your odds. It's more like poker, some do not see this as gambling as the good players can constantly place in the prize, where as slots, you can not use any skill to change your odds, unless you work out the pay out code, but thats cheating.
I would not say Skills, mobs have any factor in this (my opinion)
The mining system seems to have changed again, I have yet to try it out, but I hear its better than the boring 90% returns.
So time will tell.