Roku has snatched programmatic ad tech firm Dataxu for a steal at $150 million – half last year’s reported asking price. But why in a flourishing market of programmatic advertising – boosted by the rise and rise of connected TV devices – has Dataxu’s value declined so dramatically? The answer quite simply is that the original WSJ-reported price tag was grossly overinflated – itself undermining Dataxu’s success in providing data management software and marketing analytics for programmatic ads. For Roku, the message is clear – expand and sell ad inventory outside the Roku walled garden and do it quickly. Acquiring Dataxu is a move to accelerate the process of measuring and monetizing OTT inventory across mobile and desktop – combining…