By it being a variable that means you can't dictate to me what is fun and I can't dictate to you. We can change it to our definition of fun.
And just like you make changes for small maps I want this exact same ability for very large maps.
And it would be super easy to do. It is no more difficult then adding in any other XML variable.
The variable already exists and can be added already, as it happens. Just go to mapsizedefs.xml, find the size you want, and under the range bonus add:
This will double ship speed on that map size. Change the number in the Value scope to change the speed ratio.
What might be cooler is, rather than making it a size setting, making it a game option in itself - ship move multiplier. That way, players who want very slow ships on big maps, and those who want very fast ships on small maps are both covered.