I don't think we need a left armer for variety, but I do think we need to select our best bowlers. At the moment Australia has two bowlers in the top 3 in the world (McGrath is second, Bracken is third) while Lee also makes the top ten (he's 7th). They all have to be considered certainties to make the team.
Why leave Hogg out? Because the Windies pitches aren't likely to offer all that much to the spinners, and with the short boundaries and batsman friendly wickets, I can see a bloke like Hogg providing not all that much value. Who says we need a spinner anyway? There are no rules that say you have to include one out and out spinner in your side.
Watson is NOT a great all-rounder. Not by a longshot. At the very best you could currently consider him to be an unlucky player with a lot of potential who has so far not lived up to any of the wraps put upon him. And he's f*cking injured anyway!