From a gameplay balance perspective, the best balance is to allow dispel from a non-ethereal caster to be able to affect everyone, but to allow dispel from an ethereal caster to only affect ethereal targets. You can whine about realism, but it's magic anyway, and you can already be prevented from walking through or even opening an unlocked ethereal-warded door from the ethereal plane, so whatever, there's your realism too.
It's always been very overpowered from a gameplay perspective that you can dispel non-ethereal opponents from the ethereal plane, but it used to always come with an appreciable chance that you might get dispelled yourself. Now, dispelling from the ethereal plane is infinitely more viable now that sorcerers can enchant for MR easily which allows them to be 100% dispel-proof. Buffs are extremely important in PvP, which makes dispel magic in PvP one of the most important offensive "malediction" type spells, and with impairment coupled with the fact that it's now much more difficult to achieve a desirable will save, dispel is one of the best spells regardless of whether you're in the ethereal plane or not.
As to Arelgama's statement:
Arelgama wrote:
Sorcs have so very few offensive spells that don't take forever to cast (time enough for you to get merced) that ethereal form is their only real option.
Sorcerers have an absurd amount of potential, especially now that enchants got hit with the nerf bat. Color spray will still completely wreck unenchanted groups, and now that MP and AP are separate enchants, acid blast should do plenty of damage. Even moreso, since sorcs have every reason to max art nowadays, it's likely that the vast majority of their damage spells won't get half-saved against. Double petrification scrolls recite instantly too. That's also not even considering the vast array of damage dealing/crowd controlling magical devices. Saying that ethereal form is their only real option just because petrification takes too long to cast is like saying that because bash lags mercenaries for two rounds, a merc's only real option is to recall.