The logic behind it is that you can't beat the consistency of mono-color decks. What you lose in other colors you gain in solid cards which best fit in mono-color decks (eg: Longbow Archer). Plus, the card pool is there to build a mono-color deck.
Quick analysis of the Duals for a weenie.
- Adakar Wastes - Can't argue with this one
- Coastal Tower - If you are running 8 1 drops you seriously risk losing a turn 1 play. Coming into play tapped screws you're mana curve. The tap-duals are hard pressed to find a home in beatdown decks.
- Lairs - Again, can't play turn 1 and you lose a land drop. You don't have the time for it in a weenie deck
- The Odyssey dual - Again, a bad first turn drop. Plus these could slow you down if you are running a lot of WW or UU spells (like the Archer, Kirtar, Pianna, Counterspell, Glorious Anthem, etc.) Not friendly to Devoted Caretaker either
Not overly impressive for this type of deck. However, blue would be cool for the Meddling Mage (who you usually don't want to attack with), Fact or Fiction, and Stormscape Apprentice
Pianna (who gives the boost to herself also which the Soltari doesn't) is worth a shot in this environment b/c its a much slower enviroment then when the superior Soltari Champion (great card BTW) was around. The Champion didn't get played b/c no 3CC creatures were ever played (that I can remember) in weenie decks during the Rath-era type 2 besides Ball Lightning and Paladin En-Vec. Personally I never understood why, but I wasn't as on top of the scene then. Even still, she might be better as a Crusader, but who knows until its built.
John O's decks are cool, but neither of them are as aggressive as a mono white build. I'm sure they are better decks, but more ideas can't hurt.