unless you it make queuable, split into three wings or count as whole 5 dungs for the weekly, that would be terrible.
for one, this was the first week, alot of people wanted to check it out, even people, that dont really need the gear from it, so on average, there were better people that what can you expect the next time around, kinda like how LFR and ToS pugging are usually clean on wed/thu then often a mess later in a week
for two, the place, even with the dps we have, takes good 60-90 minutes in a good/guild group, its not as boring as the MC event was (yet!), but considering how obsolete the gear will be for raiders the next TW, people just wouldnt bother with something, that takes up to 3 hours and doesnt offer much, if anything
and for three, which is more of a nitpick tho, is the fact, that TW already doesnt scale stats well anyway and for some specs that require certain stats for fluid or fun gameplay, its just not fun not going into TW, having your crit or haste lowered by half and, not having resources like youre used to on raids or having cast times noticeably longer etc. Or add to that certain mechanics, like dispells, are different now, we dont have the possibility of spamming them now, but trash still spams their CCs, its not fun, when you pop CDs and you get whole 5s out of them because you are constantly being rooted, stunned, cursed, sleep or are otherwise incapacitated