if i have a low level lucidity dream i find this is the case.

however, i can remember my most vivid lucid dream like it was yesterday...

i think how well we remember dreams is much the same as how we remember waking life. we remember events best if we are fully in the moment when they happened.

one can have a lucid dream and not be 'fully there'. and one can have a lucid dream and be fully and completely immersed in it while it happens. the latter should usually be remembered as clearly as waking life.