This is intended behavior for a couple of reasons. The mouse selection system is part of the HUD, which is projected onto your helmet's visor. The side limits of the click range is just inside the edge of the screen on a 4:3 resolution and a bit further inside on a 16:9. It will be closer to the middle of the screen on wider resolutions. The click ranges remain the same no matter what screen width you use, they are consistent across all resolutions (so all players have exactly the same target selection options regardless of what resolution they use, no advantages or disadvantages in that regard). All other menu options and buttons also remain consistent.
For ship selection (which is all this impacts anyway), the ship must be within the edge of your HUD to click on it with the pointer. However, you'll likely find gunsight target selection to be a more accurate and functionally effective method of targeting versus off-center targeting anyway. At least, that will likely be the case if you prefer visual target selection... especially in combat.