They got at least 15 accidental runs early on, plus they're batting on a pitch where they should be able to make well over 5 runs per over. The scoreboard is what it is, which is not a measure of difficulty. Jayawardene was caught off a no-ball and Dilshan could've smashed his own head in; these sorts of things just aren't reflected in the score and if anything, it's a boost to a batsman to survive a chance. The longer the batsmen can bat, the more important that early opportunity.
So many local teams have made the mistake of batting first at Adelaide that it's arguably due to arrogance: an over-dependence on the plan of batting first, rather than showing the ability to adapt to conditions and opposition plans. For Australia to justify this decision, they needed to make close to 300, a score that might negate the disadvantage of any early tackiness in the wicket. Poor fielding gave them a chance, but Watson was scratchy, Malinga finished well and Warner's batting lacked acceleration; his strike-rate didn't really change from his first 50 to his second. Clarke was obviously a lot better at finding the pace of the wicket, but soon after his 50, he found the hyperdrive. He made 41 in 20 balls to beat Warner to a hundred from 87.
It's increasingly hard to justify making anything less than a run-a-ball hundred. If nothing else, the scrutiny is unbearable. Dilshan's big score in Hobart similarly didn't seem like enough when the night was finished and also, he was outpaced by his century-making partner. Keeping wickets in hand is definitely better than not, but not beyond the point which they are of no use. There's a need to compress the scoring as the game approaches the end, especially if lots of wickets remain intact. A batsman who has already gotten to around 90 off 100 can probably hold his ground somewhat, but a batsman only pushing 70 from 100 needs to start earlier.