Fixing weak pawns on d6 and c6.

1...dxc5? 2.Be3 White soon recovers the pawn with a clear positional advantage.
1...d5? 2.exd5 cxd5 3.Nxd5! Nxd5 4.Qxd5 Bxa4 5.Qe4+ +-

In view of Black's badly coordinated pieces, White sharpens the game.

This won't end well, but it was difficult to find a good remedy to the f4-f5 threat.

Swapping Black's main defender.

With moves like Re3-g3 and Bb3+ coming up, White has an overwhelming advantage.

Creating new opportunities on the queenside.

Speeding up the Na4-b6 plan.

With the decisive threat of 9 Rd7, which can't be parried.