Saucer separation is a matter of practicality. What do aesthetics matter? If you're in a situation where you need to go into battle and leave non-essential personnel behind, how pretty the ship is is the last thing on your mind.
What they should have done is made the whole separation process faster, given the saucer some kind of limited warp capability, and put the main bridge in the drive section. There were plenty of times in TNG I was left wondering why they didn't leave the saucer somewhere before going into a dangerous situation.