I find lius D1 to be a waste. Its the same frames as b3....so yea....
As for people poking you, liu kang MUST stagger strings to get pressure. With no 6 frame move, he gets out poked all day e'ery day.
Also, from time to time, finish F121. Every player in the world knows liu comes in with F12, so complete the string and send em full screen to reset your zoning. Or if you are really feeling froggy, and you read they like to poke after F12, give em the F12xxEXlowfireball.
Moral of the story is, despite being rush down a lot of the time, liu LOSES the down poke game to almost all of the cast because of 6 frame d1s all over. Dont be predictable. 334, b2,3 and b2,b3 are all good neutral pressure strings to keep your opponent honest, and F4 is gold.
Liu is SO MUCH MORE than F12, 213, B312