Actually, with the advent of the next-generation variable warp field coils, the damage done to subspace was at the very leaste minimized to a level that Starfleet apparently found acceptable. The Intrepid class's swiveling nacelle pylons were apparently part of the beta testing. Once the Sovereign and newer classes were appearing, the new design had been perfected and the pylons no longer needed to swivel.
*re-cloaks and resumes lurking*
Slashdot Mirror
Actually, with the advent of the next-generation variable warp field coils, the damage done to subspace was at the very leaste minimized to a level that Starfleet apparently found acceptable. The Intrepid class's swiveling nacelle pylons were apparently part of the beta testing. Once the Sovereign and newer classes were appearing, the new design had been perfected and the pylons no longer needed to swivel. *re-cloaks and resumes lurking*