With all this new technology they are using in cricket has been useful with assisting the umpires, it is beaming more and more apparent the umpires are overruling everyone. Since when has it been, that they decide if its too dark? Didn't the batsmen always get offered the option to bat on or go off? Apparently now the umpires just make that call alone. Obviously there has to be concern for batsmen and the bowling side with the lighting issue, they don't want players to get injured if they can't see out there, or give an unfair advantage but the players really should dictate this decision.
As for the no-ball wicket one with Clarke, I've got no issues in the sense the umpire wanted to check just incase, and he went with the right one, but I do believe that if the umpires can see the blower may be borderline with each delivery, is perhaps mention it to him or mention it to the captain instead. Rater then wait for a situation like this of the 'suppose' ticket? Umpires never have issues with warning players, calling no balls and telling bowlers off for running on the danger area of the pitch, so there is no reason why they can't just give the bowler a friendly reminder to them they might be close to over stepping even though that should be the bowler's responsibility, nothing wrong with just passing on a message. Still the decision was the right one and without the kind of technology available, you can only imagine what the uproar would have been if it wasn't called back. There would be so much abuse going to the umpires for getting it wrong. Just think back to a test match in Perth between NZ and Aust, when Warne hit a ball high and long and he was in the 90s...99 I think and he was caught? It turned out he was caught off a no-ball apparently, and at the time lots of people said it was outrageous the umpires got it wrong. though the revelation didn't come till a few years after that game.