In party situations, I'd tend to agree with Raenryong, however for soloing or skill ups and other niche situations, this could be a nice alterative piece to avoid -10 eva from hauberk, but for party scenarios, best to go with something that helps the group the most, and other pieces do that better. Otherwise it's a quality, no frills piece.
It's called a macro. The general idea is you equip some things that will enhance the action you want to perform, then you perform the action, then you equip back into TP/idle gear. For example, you /equip Jump gear, then you /ja Jump, then you /equip TP gear.
So with the VIT out of the way, your argument is that 3 STR is better than 6 accuracy? That's like telling people to use Sun Ring over Sniper's Ring. There's just really no good reason to TP in this on DRG.
And if you really think your accuracy is capped, then eat meat. If you still think your accuracy is capped, then...why are you wearing this?
This piece should be at or near the top of the list for a RDM75 who wants a melee build. I personally prefer this piece to the SH, not only for its generally lower cost, but also (as noted in other comments) for the added STR and VIT not generally available in RDM-wearable armor. This is a well-rounded piece for both RDM/NIN and RDM/PLD builds.
This is honestly a great body, i use this body 95% of the time as RDM/BLU.The VIT+3 helps with a defense set up and the STR+3 helps with Vorpal Blade which you unlock as /BLU
If you're a DRG and you don't have an Assault Jerkin or Barone, do yourself a favor and use this instead of SH.
The 3 STR and 3 VIT will help your damage much more then the 6 acc you loose. Your A+ Polearm rating should be enough to make you hit, maybe with some little added acc from Chiv Chain or Tiphia Sting.
And yes, VIT helps a DRGs dmg, since it mods Jump ....