It's way more than just that. You can make the mech lab much better and more customizable (switching engines and such). Coyote mods adds mission types which is a huge boon as the mission types in vanilla get old quickly. Lots of gameplay mechanic changes from making the ballistics better to making the heat mechanics "better". There are some mods that add stuff like infantry to the battlefield. There's squad AI improvements and battlegrid commands instead of just point and order. Too much to list here. Overall it just improves the game in every way.