Remakes of the early scenes started long before Steam was even on the horizon.
They came about because Z had improved to such a degree in the visual department, that he grew dissatisfied with his earliest work and decided to tune it up when he felt it didn't represent his skills adequately anymore.
It makes sense to have a more cohesive quality across the game. Even though it was interesting to see the progression as the updates came out, a new player would probably find it jarring or not be taken in much by a game that has a cover page of a certain style, and the first scenes of a notably lower quality.