These openings are considered "irregular," and therefore not totally reputable. There are two reasons.
The first reason is that unlike c4, d4, e4, and f4, they do not begin a fight for the key center squares. You can make the case that b4 and g4 open the way for a bishop to be "fianchettoed," but they get the player "involved" in other ways. B3 and g3 are "safer," but lackluster versions of these moves. And the pawn on g4 blocks the bishop on h3 unless you move it further. But in any event, white is likely to get behind in development with such an awkward, clumsy opening, even though s/he shouldn't by virtue of moving first.
The second reason is that kings generally prefer to castle into the corners on one side or another. These moves of side pawns open up the corners prematurely, making it hard for your king to castle. They may be good moves LATER in the game (depending on the situation with the OPPOSING king), but playing them on the first or second move gives the opponent too much time to take evasive action, thereby robbing you of the potential benefits.