Well, during the extended beta I made a lvl 50 Bounty Hunter, and while I went mostly purely Light Side I didn't really use many pieces of equipment or items that were LS restricted so I wouldn't say any of the "best" items require LS or DS points, but some stuff like the equipped Relics do. So while there isn't any real detriment to not choosing one direction, there definitely isn't any positives to staying neutral either. Personally I've been choosing the answer that best reflects what I think my character would choose, it ends up being mostly LS with a few DS options. I guess in the end though, you can always do replayable Heroic Missions and Flashpoints to try boost one over the other... if you stay truly neutral... that could take a long time. I read somewhere that BioWare doesn't plan to add neutrality bonuses as they feel you should pick a side.
"Women are like sunsets… they’re beautiful, but there will be a different one tomorrow." - Gilder