To trade you don't need to use the zones, you only need to see what zones border the water you border yourself. But being able to attack ALL zones that border the sea would be too much I think, so I might cut the seas into sea regions in game 2 if we're going to wage wars on the oceans. They will be larger than the zones however, so controlling one sea region means being able to attack a big number of zones.
Right now, it doesn't matter the least what zones you attack (except for the small strategic advantage of wiping out the enemy coastline so it can't trade, or gaining coastline with someone you want to trade with). So in that sense, the game needs more strategy. In game 2, I might add the ability to reinforce some or all zones, so you can "stack" armies on them, like the enemy having to use 4 zone points to conquer it instead of 2. But it might be a good idea if I added some ressources to the zones and made them different, so they wouldn't just be all the same.