I must have completely missed the part about why there would be more swampies in pvp, over faction horses and other things?
Because a swampy can have over 250 hit points, and the resists on a good quality swampy just went from this:
35 27 35 28 40
To this with exceptional verite barding on it:
80 63 61 63 60
You take the time to train them up and you have the hardiest mount now available to a non tamer. Now of course, I'm always thinking like a tamer, so maybe no one else will even consider doing this. And I must admit, 750 verite ingots is a pretty steep price to pay for something that won't last more than a few days of heavy usage.
I haven't checked out what the resists would be like with iron barding. I'm going to do that right now:
67 48 50 48 52
So even with iron that's a pretty significant boost.