The reason for the serrated triggers was to gain extra points for importation. The fullsize guns did not need those points, while compacts and subcompacts benefit from the 'target triggers'.
PS: Notice that the tactical/practicals (G34/G35) and longslides (G17L/G24/G24C) don't have the same 'target triggers'.
Ron W. - south of Atlanta
Certified Glock Armorer - Oct.2010
GlockTalk Clubs- #10 Georgia Glocker; #3745 Bull Dawgs; #600: 10 Ring, .40S&W, Sub Club, Long Slide, Niners, Wheelhouse, MilSurp, Rimfire, 1911, Black Rifle