The Primals would have had more life expectancy if getting a Relic weapon wasn't so easy.

In 1.0, it took a lot of effort both in time and gil to get a Relic, on top of that it was all group content and was 'arguably' difficult - Ifrit Extreme was the same kind of learning experience that Titan Hard is (though I personally liked Ifrit Extreme better because of the diversity in what could happen during the fight and what needed to happen during the fight).

In order to do Ifrit Extreme, you had to farm gear and get melds, get Darklight. You HAD to farm Garuda to get the necessary DPS to take the nails down. This made Garuda relevant and a necessity to farm.

In 2.0, you can do a relic in 1.5 hours sans tokens. There's really no reason to farm the primals, they are DoA.

Add on to this that it is extremely time consuming to properly gear multiple classes (in a game whose niche is playing all classes on one character) it is very discouraging to play classes that aren't alike (WAR+PLD, LNC+MNK-BRD, BLM+SMN, WHM+SCH)

With the ease of Coil pre-Turn 5, I wouldn't have a lot of hope that Crystal Tower will be particularly difficult. Twintania is only difficult because of gear and will become much less difficult for groups attempting her as more people in each group get iLv90 gear. We are making solid progress and the only people with any Allagan/AF+1 are our healer and BLM. I have a shield and curtana+1 but certainly not enough HP to comfortably survive every time. That changes with 300 more HP, easy.

Will Extreme mode Primals also be DoA? It depends entirely on what they drop and what their completion is relevant to. If they drop more weapons then they aren't really of much help to anyone because damage isn't an issue (now) in Coil.