I think by investing into 2/3 improved shields for a personal dps boost (no matter how small) is a selfish choice. As Krustsik said, totemic reach also gives a dps bonus: . It's also important to note that a fire elemental is less tethered, and that is a totem which you can't re-drop. More importantly, however, is the utility totemic reach provides for other totems besides fire. For example, I drop earthbind totem on H Nefarian for the Dominion Mechanic. If an earthbind hits someone who would otherwise be out of range, their damage/healing would be increased by that much more. The same idea applies to any fear mechanic that requires the use of tremor.
tl;dr Put points into improved shields if you want your damage to increase. Put points in Totemic Reach if you wan't to kill the boss.
Going to say this again, smart totem placement makes TR pretty much useless. Granted, some of those points are valid...however I wouldn't agree with your last point at all.
I would agree TR is useful on nef/cho'gall/maloriak/halfus depending on what strategy your guild uses...it isn't for mine. On halfus my guild clumps all adds in one location...nothing is spread out enough to make TR useful for me. On Cho'gall, we don't use a fear/tremor strategy for the adherent phase (we spread out)...however if we were I would probably pick up TR because I have to respec into reverb for that fight anyways. On Nef, we usually run with 2-4 shamans and 1-2 hunters...in phase 1, binds/traps are dropped on both melee and ranged...and for p3 we clump together and I drop the totem in the middle of the radius the tank slowly turns him (again this varies depending on strat). Additionally, the earthbind debuff has a 4 second duration, which means if it pulses on the edge of the totem range, it's still going to last for 4 more seconds of slow...it's not like frost trap in that regard.
So in short, yes, TR is useful in some situations. Before you pick it up I would really look over at what strategy your guild uses for every fight and decide whether it's really best to take based off of judgment. If you know for a fact that you can strategically drop your totems in good places every fight, you shouldn't need to pick it up. I've seen a lot of shamans underestimate the placement of their totems so many times and have had to redrop them...but one has to realize it's part of our class to both know and learn the best positions for them on any single fight.
TLDR again: picking up TR is entirely a judgment call on your part (or your guilds part).