Making all the dungeons soloable means that Funcom would basically have to rewrite each encounter as every boss in t4 requires groups now to do them.
Might as well just put the time into making new dungeons or upgrading older dungeons into unchained lvl 80 solo ones.
Can you really expect to get Funcom to reprogram every one of the bosses in t4 that right now require full raids (or near full) to do? You have 12 people bound up in zodiac to start doing puzzles plus the tanks and healers...how can you do that solo? And sixman puzzles in there? CCing the symbols?
It would be easier to make new dungeons.
And, yes, I am in a tier4 guild. I joined when I joined Set and have worked to get a spot in raids so I can get gear. I still do not have the t4 dps bear shaman hammer and my demo is certainly not full t4.
Break T4 into two dungeons: that can fix any memory cloud issues and make it easier for pugs to do lower anyway. I saw a pug t4 on set last week so they can happen.
Giving away t4 gear for soloers...especially eight relics a run...the raid was developed for group mechanics, not a soloer. Solo stuff should never be as good as a group/raid items because a raid takes a lot more coordination. And I do prefer soloing to running groups for anything but sixmans or raids.