Ships can move in more directions relative to their normal frame of reference than just "forwards" and "backwards." Is there a range of maximum speeds dependent upon how close the ship is to moving directly forwards or directly backwards? Is there an arbitrary range of directions relative to the ship's normal frame of reference such that movement in a direction within the range is considered to be "forwards" while movement in a direction outside of that range is considered "backwards," with or without some additional range of directions for a transition between maximum speeds? How is purely-lateral movement affected by differing "forwards" and "backwards" maximum speeds? If I'm coasting forwards and rotate my ship to bring forward-arc weapons to bear on a ship following "behind" me relative to my direction of travel, do I lose speed if I'm above the maximum "reverse" speed? How about if I'm not at the maximum "reverse" speed?
Implementing distinct maximum speeds for forwards and backwards movement is not as simple as just slapping in a new speed attribute for the ships, and the current system is in my opinion good enough as is.
(this is also why weapons have maximum ranges)
Weapons could have maximum ranges to represent that not all weapons necessarily have the same maximum
effective range in space even if theoretical maximum range for unpowered projectile weapons is effectively infinite.
Factors which can realistically limit maximum effective range include but are not limited to sensor accuracy in determining bearing, range, and velocity information on the target, turret rotation and elevation speeds and accelerations, beam spread for laser-type weapons, recoil-related issues for dumbfire projectiles, powered flight envelopes for guided or homing munitions, and target-motion prediction accuracy limits.