h2 to h3 after 0-0

I have read that the pawn move from h2 to h3 after 0-0 weakens White's defense.  Is it because there is only one pawn that can attack g3 or some other reason(s)?  In this position, white has pawns on f2, g2, and f3.  The king is on g1.  Would someone provide some examples of how h2 to h3 can be exploited? 

Phobetor's "Beating the Najdorf" blog is an example: http://blog.chess.com/Phobetor/beating-the-najdorf . Because Black played h7-h6, there was only one pawn left defending g6. Just one sac (Nxe6 fxe6) and White was able to play Bg6+. Of course in that case the king was still on e8.

Say White plays h2-h3, and there's a Black bishop on the a7-g1 diagonal, then pawn f2 is pinned and g3 is not defended at all.

If White is forced to play g2-g3 at some point (say Black has a bishop/queen battery on the h1-a8 diagonal, or a rook/queen battery on the g file), then pawn h3 is left undefended and g3 is only defended once.

Often attacks involve a pawn storm, and after h2-h3 Black only has to move g7-g5-g4 and he already threatens to open up the king's position with g4xh3. If the pawn where still on h2, g4-g3 would be one move extra and onto a square that White has covered twice.

I can't go looking for concrete examples right now.

Thanks Scarblac.  That information was very helpful in understanding this position. 

thanks scarblac

If the king gets any hassle from enemy pieces/pawns in front of him its easier to push one pawn to stop this and give him more time to defend! If you have pushed Ph3 earlier and pawn on g2 is under much pressure thne pushing is harder to defend as It is only defended by one pawn and also the h3 pawn now becomes weak.

That is pretty much just reinforcing what the guys above are saying. In general its stronger to have no pawns pushed in front of your king!

But its not always bad, sometimes its necessary. It helps prevent back rank mates later in the game, and early in the game if d4 is an important square you want to play h3 to stop a Bg4 pinning a knight on f3.