Can we not just say that both runners are impressive, though in different ways? Mottram ran some super ballsy and impressive performances again Africans at a time when no one was doing that, which made him quite the badass. He also may have overraced (see above post about # of races per year), decreasing his longevity, and possibly contributing to his somewhat sparse world champs/Olympics resume (only one top 8 performance outdoors aside from bronze in 05).
Fisher is running in a very different era, with much faster times and more non Africans who are relevant at the global stage. He is a great time trialer, and has some solid but unspectacular world champs/oly finishes in his 2 attempts. Has he shown the cajones of Mottram in championship races, taking the lead against the likes of Haile and Berkeley from over a lap out? No, not yet, and maybe never will (though I hope otherwise). And is the racing schedule of the BTC team a bit frustrating? Yes absolutely. But he is probably setting himself for more longevity in his career, and it wasn’t like he ducked big diamond league competition this year to run fast times (his 1246 and 728s were diamond league races after all).
At the end of the day we can respect Mottrams fearless approach to racing, and acknowledge that top Americans (eg Rupp, Fisher) may end up with more accomplishments at the world stage by taking a different approach.