It wasn't a bad idea in that it hurt the quality of the series, but it was a bad idea in that it was pointless.
Episode 7x?? - With Warp Limit
Captain Picard: Set course for Rigel IV. Warp 8.
Episode 7x?? - Without Warp Limit
Captain Picard: Set course for Rigel IV. Warp 6.
Yup, that sure did do a thing. The ships are going to travel at the speed of plot regardless of what numbers are thrown at us in dialogue, so I just don't get it. Silly analogy for environmental protection is silly.