Downtube mounted cable adjusters seem to be going out of fashion these days (aerodynamic reasons?) and are being replaced by inline adjusters (or nothing at all). As Hillrider noted, the new rear derailler will come with an integrated adjuster so you don't technically need an inline adjuster there. For the front derailler, some people get by pulling the cable tight with pliers but I much prefer to use an adjuster. The fine tuning ability and future adjustment ease are well worth the added install time in my opinion though.