I disagree.Grunts
The class has perfect reasons to have diplomacy and tumble.
In Pen and Paper, Dragon Warriors get a charisma bonus when talking with dragons of the same blood as they are.
Furthermore, dragon warriors often share hideout with dragons, or at least very closeby. This means mountains most of the time. Now, tumble is the best standin for climb.
As long as tumble gives the ability to jump in and out of melee combat and +3 passive AC it has little to do with climbing. Furthermore feats of Dexterity are one of the few things Dragons are NOT good at. So it makes even less sense for a Dragon Warrior to have Tumble then many others without it, like Fighter.
As far as Diplomacy goes, getting a Charisma bonus toward a single race does not equal being more diplomatic in general. Diplomacy simply has nothing to do with the Dragon Warrior class. A fact even further realized when you read the rather limited class description:
http://www.bgtscc.net/viewtopic.php?f=7&t=7826&start=15