Improvisation

[CKNovel]

You have it backwards, MCH got extra support because DNC and BRD both were more popular than it. Now that MCH got the wrench (what I most wanted for it to get back from its HW kit) it is equally valued if not more in circles for its superior dps compared to BRD and DNC.

Warden's problem revolves around encounter design and is actually rather functional, while Improvisation suffers from both encounter design not catering to it and not functioning well for a support ability. And you know what, I want Warden's to be used more, it's also fun. Let BRDs have more usage of their interesting buttons too.

No, DNC was dominating too much the ranged role and will keep dominating the ranged role until they remove the single party utility.
Dance Partner is simply too good and now has a new potential partner, the Viper.

The problem is that you compare DNC, BRD and MCH together but you need to compare them when they're in a full team.
DNC is a job that perfectly fits in the 120s meta AND repetitive downtime design of many encounters.
DNC also works incredibly well in early savage thanks to gear funneling.

Improvisation is a 5% shield at minimum, Dismantle is 10% mitigation. Shield is often stronger than mitigation, as the more mitigation you stack the weaker it becomes, a 10% mitigation can become a 5%.
On top of that, DNC has Cure Waltz, which is the equivalent of a Medica III.