I would not say "Make the game better" but rather raise the level of complexity or the level of details.
For example, the "Wizard kings" board game use a plain hex map as a board:
http://www.boardgamegeek.com/image/200018/wizard-kings
But movement looks much more complex than it seems. First, you get mobility boost if your unit start and ends on a road. But most importantly, there is a limit in the amount of units you can move into a hex for each hex side. So an open plain hex side allows you to move in 2 units, while an hexside with a bridge or mountain only allows you to move in 1.
So this creates a dynamic where in order to send a large force into a target hex, you need to be able to surround your enemy. It also create interesting simulation of blocking a bridge to prevent the enemy from passing since he can only send 1 unit at a time.
All that added complexity also increase the possible effects that special abilities, like spells, could affect. Instead of having spell that increase movement or ignore terrain movement penalty, you can also add abilities regarding the hex sides and roads.
So restrictions increases the complexity and details of the game. It open what I call "the area of effect" of a game which is the possible elements that can be affected by a special ability. But it is not always the best thing to do. In some design, you might not actually want that extra level of complexity and detail. In video games, complexity is more welcomed because the computer can compute stuff for the player, but it's no the case in board games.