It has trample at 8th level on my class as well on the MM II entry from where it came. Mind you the original monster isn't that hot since like all giants the normal version barely has abilities.
Also, well, trample is kinda of an iconic giant ability.
Giants should have powers related to their theme (fire, earth, wind, water,heart, by your powers combined I'm captain giant planet!eerr, nevermind the last one).
But they also should get a touch of GIANT SMASH! on them since giants shouldn't be big for nothing. When you see a giant, regardless of it's race, you should fear he can literally run over you!