For one, it’s a significantly more difficult engineering challenge. Two, it’s unprecedented. OSIRIS was cinematically more dramatic, but we’ve been hitting moving things with moving things for a while. We haven’t done a mechalox reusable massive spaceship before to the point that it’s basically its own category.
Maybe it’s just me, but I don’t find landing a rocket to be terribly impressive. Especially when it’s literally the least critical feature. We can do successful missions without the still very questionable reusable aspects of this extremely late and extremely questionable system.