The reason I see it's good to have primary stats is to give you the choice between one of three. Mainstat (DPS/EHP hybrid), Vitality (EHP) or Resist (EHP). Since there is no more double stat, this is what you get out of a socket and what the affix roll should be. The single gem should never allow you a higher number than what an item affix would roll. Helms/weapons are big offenders of this but multi-socket chest/legs are the other. Iactually see sockets rolling on rings/amulets/shields to be OK and nothing is really wrong with them.
I talked brief about this on the incgamers podcast, but making gems doing something other than stats is really the jewel system from D2. However, the storage of all your jewels, since they'll all be unique in affix rolls and non-stackable would be an inventory nightmare and we all know the storage issues that come up with RoS, especially with BoA items taking up a lot of room. It still boils down to the primary problem is that sockets are, more or less, a required affix on items that can roll them especially if you can get more than 1 (pants/chest) or the single off-stat affix that you can get out shines everything else (weapons/helm).
I wouldn't really mind a re-work to be +primary stat. But in some cases though, having a small level of dex to get some dodge is usually accounted for on builds and right now you cannot get enough off-stat rolls because there are no more double stat rolls to get them from. However, the values of dodge dropping considerably is a whole other issue that came with the beta. But if you're adding varied affixes, the socketing system bleeds back into the old enchanting that the Mystic was supposed to do which is something that Blizzard already moved away from.
I really think that pulling back socket rolls on chests/legs to 1 socket a piece is more reasonable to open up getting other affix roll possibilities. Then changing up the rewards for gems in weapons and helms so that the single affix can no longer be some hog wild level of statistics.
I just don't see the changes as being real choices. The item is telling you what to put in, there is no choice except what grade of gem to put in. Also, requiring a gimp to overall DPS to gain some bonus might not be worth it. In the example of the Phalanx item, if you put your back to a wall, you don't need any more extra Phalanx so you wouldn't see anybody putting topaz into their items with exception of the required topaz.
The first one has some choices, but involves 3 times the work to implement/test legendary affixes on items if that's the case. I'm more in line with what Noxious had suggested and that is removing gems and making them something you apply to items with something from the blacksmith at a cost of legendary crafting material to make the idea of having sockets more permanent to an item. I'd even be more for chest/legs rolling only 1 socket as well to bring them more in line with other stats.
http://www.diablofans.com/builds/71386-rank-11-the-thrill-gr45-build was mine that disappeared. Turns out I was in the wrong forum looking for help.