Actually it did.
It capped out at 204472.31 km/s (about 2/3 of the speed of light).
In ED we can fly about 2000 times the speed of light in supercruise.
Yeah that's what I thought in the very moment of writing my post. I suppose Mr. Braben was afraid of relativistic effects and introduced this limit

. 'A bit' more than 300 m/s...
As for the supercruise - OK, I know, but as we already have Newtonian flight physics with Flight Assist off, why not give it a full blow - one wants to supercruise, another one would prefer a bit of wandering using traditional drive. Maybe there will also be a Lifter or Escape Pod without FSD - it won't get anywhere with a speed limiter. How to land on planets if excessive mass pulls out of super cruise? :-]