Why the War Doctor Was a Pointless Act of Creative Cowardice

It's been almost a year since the landmark 50th Anniversary episode of Doctor Who aired. Upon repeat viewings, the episode does still hold up, but there is one thing I now find irksome; the War Doctor really didn't need to be there. Either the 8th or 9th (preferably the former) would have functioned in that role without a massive retcon and the creation of a zero sum character. Let's look at Moffat's reasons for bringing in the 8.5th Doctor and see why they are invalid and just created more problems.