Tiers 1-3 were made 'skippable' long before Ikky and adept changes by the implementation of high end tradeskill armor, because imp hide, deepmetal, etc. were balanced around tiers 2-3.
It's okay, not all players will choose to spend their money on tradeskill items or ikky drops, many will want to 'earn' their items as they level at a level-appropriate challenge. They may not always get to kill every adept, and if they did, they may not fill every slot.
Having some t1-3 no drop raid targets does not cause problems, even if they don't get hit all the time.
Although, if they need love: they may be a better solution to be used for quest pieces than mid-tier and other contested raid targets.
BAM, there it is. A lot of these targets get hit frequently regardless (when's the last time someone saw every WW dragon up at the same time?). Between dragon scales and sinews up to unique items like WR bags, lev clickies and remove disease clickies, there aren't a lot of even low tier raid targets that don't get killed pretty regularly, if even just for ancient spell scrolls. Excluding Telvosh of course, who nobody touches even with a 10 foot pole.
At every tier there are drops that make you go "OHHHHH GOD YES" and drops that make you go "eh" and with fairly regular frequency make you go "@!#!&$@(" (lookin at you, Flametalons).
Tier 1-3 has a solid niche in SoD. On rare occassions, there IS the guild that wants to progress naturally from A to Z. More frequently than that, there are alts or fast-up-and-coming higher tier guild replacement toons that want to farm out the lower tier mobs like WW dragons, Lavascale, Gnok, etc for things like ancients or one of a kind clickies/items. Even these higher tier guild farmers will USUALLY /ooc or at the very least /who all XX and /tell RANDOM GUY "Hey, going to go kill BLAHBLAH mob, he might drop/is holding/can drop GREAT ITEM FOR YOU THAT WILL ROT OTHERWISE, get your ass over here real quick so you can scoop it." Then that player has an item that, being an obviously casual player for not already having better, he/she will cherish for eternity, and an experience he will not forget.
"Remember that time when Jenks sent me a random tell and said "hey, summoner in cmal is wielding a twilight rapier, it's going to rot, get your ass to cmal and it's yours"
I sure remember it.
The GREAT thing about this low tier now-non-progression-neccessary content is that it allows an even greater opportunity for socialization. On progression targets that are "neccessary" we get awful awful awful awful awful damn crap like the obvious guild drama over yclist/spires. With stuff like undesireable tier 1-3 content, people are people, tier 15 down to lvl 55, nobody really cares, it's just a matter of "hey guy, let's go slay a dragon and scoop some phats." It's the real spirit of SoD shining through, because there is no disporportionate (i'm really drunk, spelling is out the window) self-interest clouding comraderie.