Dragon Soul is very stacking orientated. This is all Mists raiding which may well not be like that, if there is stacking then yes the Glyph is useless, but it may not be. In spread out fights if you're not using CH at all because people are too spread this would be an increase but it comes at a downside. Take Madness HC for an example. If your guild was struggling to heal through the Parasite damage or the bosses AoE or the slams in the platform phases, but did fine during Cataclysm and p2, you might take this glyph to help out. Obviously its unlikely that this would be the case on Madness - especially with the nerfs - but that doesn't change the fact it COULD be the case, and this glyph would help this problem as long as your other healers could pick up your slack during p2/cataclysm.
No, in DS it would not get more powerful really, but its not meant to be a pure numbers increase, its meant to be a glyph that you use based on the mechanics of a fight. Glyphs are not meant to be pure number increases anymore, they are all choices and this is an interesting one for Resto to pick from. FL did show Shaman spread healing was a concern, and this would massively help it. Sure if there was more fights like Ragnaros in Mists - a lot of them not just 1 or 2 - I would worry about the state of Shaman, but if its just one fight or two, then this glyph does the job at a reasonable loss.
It makes a niche spell usable outside of its niche at a reduced rate. Thats good. Niche's are interesting and change game play. You can't say you want to go back to WotLK where you just spam CH. If CH was the best option for healing even when your spread out all you would do is cast it and nothing else. Thats the point of the Glyph, it allows you to use it when spread out without making it so that ALL you cast is CH which is what would happen otherwise. If they just nerfed the healing CH did then you wouldn't cast CH at all, with double length jumps and no downside its one extreme or the other.
If you're in a fight with absolutely no time to cast LB then it may not be used, say you normally use Riptide, Healing Stream Totem and Telluric Currents but theres not much time to use Telluric Currents because theres lots of AoE damage, you could take Glyph of Water Shield instead (assuming Water Shield didnt proc from said damage and thus would actually give more mana back without the glyph). I agree TC does seem pretty mandatory at the moment as it looks incredibly powerful, I can even see some Resto Shaman taking Unleashed Lightning Glyph over Healing Stream Totem and going Riptide/UL/TC as their glyphs, but I still like the mechanic, its different and allows more depth of play in the class, do you do a Healing Surge then a LB or do you cast two Healing Waves? ect ect
What problems would those be? Beyond the range of CH I dont see any 'issues' fixed by Glyphs at all. Maybe Unleashed Lightning could be included in the "fixed problems through glyphs" category. Everything else is interesting, new mechanics or mechanics they have decided to make you choose rather than get baseline like Ghost Wolf snare protection (just like a lot of things have been made into talents for some classes instead of baseline - Shadowstep or Preperation for rogues for example)