In the Barry attack one of the key motives is to play Nf3-e5 and h2-h4-h5. The bishop is much better placed on e2 than on d3, as the bishop on e2 supports the pawn push.
Also, on d3 the bishop is staring at a black pawn wall (g6-h7) which limits its scope. Last reason why not to play Bd3 is that white doesn't have to worry about an eventual e7-e5-e4, attacking both Knight and Bishop.
What means this?? white would have to play c4 or c3
Bd3 and Be2 are both ideas. I think personally I would prefer Bd3. The problem is the drawback of whichever you choose may be exploited by your opponent, since you are not developing the move in secret.
Back will prepare and play c5 ad you have no e4 there!!!
First of all 5... Nbd7 is a mistake due to 6.Nb5!. Second , White puts his bishop on e2 to help h4-h5 push after he plays Ne5 .White wants to open up the h file at the earliest and play Bh6. Then he exchanges off the dark squared Bishop and builds up a King side attack. This is White's primary plan ; but Black can put impediments on the path and then White will have to adjust his play accordingly . Still he changes his plans only if his primary plan is scuttled by Black. More over, in Indian defenses a better square for the KB is often e2 ;though in some variations Bd3( Modern Benoni -h3 variation for example) is seen. This is more so when White can play e4-e5 and occupy e4 with a piece or when he wants to stong point e4 square / prevent or delay f5 by Black
When Black fianchetto's the Kingside, the Bishop rarely goes to d3. See the King's Indian Defense as a prime example, 6.Be2, not 6.Bd3. The reason is the Bishop is biting on granite against the fianchetto structure.
Also, the Colle is no good here. 6.c3 is a horrible move. The Colle works against systems with e6, not g6. This is why there is no one catch-all system that words, and those that think there are are delusional.
Colle - Works when ...e6 has been played with the Bishop behind the pawn chain (QGD and Nimzo setups). No good against Fianchetto Systems or Slav setups with the Bishop outside the pawn chain.
Torre - Works when Nf6 and either ...e6 or ...g6 have been played. Fails against ...Nf6/...d5 structures because of 3...Ne4, which is very strong for Black.
Veresov - Works against 1...d5 and 1...Nf6, but you must be willing to directly transpose to a French if you want to retain any advantage in certain lines. You'd need something else against the Modern (1...g6) or old Benoni (1...c5)
London - Fails miserably against the Modern Defense (1...g6) if Black plays the right lines.
English with 2.g3 - Play "automatically" with 3.Bg2 and 4.Nc3 fails to 1.c4 e5 2.g3 Nc6 3.Nc3 f5 4.Bg2 Nf6 and White has ZERO advantage because after 5.d4 e4, the White Knight has no useful place to go. Instead, 1.c4 e5 2.g3 Nc3 3.Nc3 f5, White should play 4.Nf3!, answering 4...Nf6 with 5.d4 e4 6.Nh4!. The Knight tries to entice g5. If Black plays it, the Knight will go to g2, attack with h4, enticing g4, and getting the f4-Square for the Knight. Despite the 2.g3 move, the Bishop should be developed classically to d3 or e2.
Barry Attack - This really only works against the KID or Grunfeld. All other lines the Barry is useless.
I a play the gruenfeld as black and is wondering why white puts the bishop on e2 instead of d3.d3 looks like a more active square for the bishop. Also,why does white play h3 in many barry attack positions.It looks like Bg4 is impossible for black anyway because of the night on d7.
Any imformation would be extremley helpful. Thanks