In itself, posting warp 10 as an insurmountable barrier, to establish the feeling 'warp technology as we know it cannot be enhanced indefinitely without some fundamental breakthrougs, and we're already starting to straddle up against its upper barriers, as we find it harder and harder to reach ever higher speeds' wasn't bad in itself for the TNG universe. They hadn't considered the writer's need to continually 'up' specs of new ships to make it sound 'even awesomer!' though. Going from 'we may be able to match hostile's warp 9.8... but at extreme risk' to 'maximum sustainable cruising speed of warp 9.975' in a mere 7 years sounded slightly ridiculous to me.