With things like third party DBMs coming to XIV... when are we getting addon support?

[Granyala]

Third party tools are never necessary. They are a crutch.

You are very naive.
The worldfirst crowd WILL use them to get an advantage.
Other people competing for cutting edge progression will either have to use them too or they will be slower since having a DBM WILL make things easier.

Once the top tier crowd uses these programs (assuming SE doesn't go on a banning rampage), usage of these programs will trickle down to the more average groups, because they also compete with each other (just not on a WF level) and they too want to be better than the competition.

It isn't a question whether you need these programs/addons from a gamedev perspective.
Take it from a WoW-Heroic raider: you don't. Not even in WoW. The devs put everything you need right there in the game.

But having predictions / ability cooldown displays make stuff easier (A LOT easier) and that's why people use them.
Also, rearranging the information displayed and using multiple channels of perception makes stuff easier to read / notice. Esp with audio signals, because typically your visual perception is already quite taxed during a boss fight.

In the end players are about efficiency. They want to do the hardest bosses possible for them with the least amount of wipes they can get away with.
Any tool or addon that facilitates this goal WILL BE USED until the developer breaks it.