Italian Game: What move would you play in this position (white to move)

My chess engine shows that Bxe6 is the best move, I played that move in the game and I never understand why it's the best move, isn't the double e pawn provide extra protection to the d6-d5 pawn break? And also open up the f file. 

I kinda know why this is good for white cuz somehow d5 for black is not a good plan as white can just allow dxe and black's pawn structure will then be terrible. Whereas white has queenside space advantage white can play Rb1 and slow pushing pawn on the queenside since black has no counterplay in the center.

Any experienced play can tell if my statement is correct or not?

Bxe6 then b4 a4 and a5 followed by Ba3 and d4

I think Nbd7 to avoid queen trade and wait for ...dxe4 dxe4 which black would have isolated double pawns in the center while you get some free space on the queenside with tempo and continue to slow attack the kingside. there are also lines after b4 you can play Qb3 to either support further queenside or kingside attack from the long diagnal. the engine often recommends some meaning move for black as the position has no counterplay for black but still its pretty equal.