Innovation in ad tech is a tough gig. Improving the ad-supported viewing experience is like consistently taking painkillers for an ailment, rather than seeking a cure. Sometimes, unfortunately, there is no cure, and so ad-supported TV marches on, unremitting. The point is that the R&D side of advertising is often overlooked. Organizations are channeling multiple $millions into innovating in ad tech – and one that consistently catches the eye is Roku, which has had a busy few weeks on that front. The ad-funded connected TV maker has introduced a swathe of trend-setting new features with the help of FreeWheel, of Comcast ownership fame, while releasing what claims to be a first-of-its-kind feature by allowing viewers to purchase products directly through…