Because right now the vast majority of our power and defense are exclusively left side pieces to the point that accessories can be 20+ ilevels lower with a few melds stay BIS. 220 crafted accessories were bIS from 4.0 to 4.2. I just finished pentamelding my 250 accessories yesterday. I will wear them until 4.4. I will cry every time a tank accessory drops because it might as well just be a middle finger to my raid group. All this because they don't scale our primary damage stat like every other class (even healers).
Theres 2 problems.
1. Players want gear progression like every other class. Meaningful. Worthwhile. Players don't have that now.
2. SE doesn't want tank damage to get to high and wants to separate defense and offense stats to balance content more easily.
So what are the solutions:
* Make vit our damage stat: SE tried it. SE didn't like it and the reason they told us was they wanted to be able to scale defense and offense separately. If they are 1 stat its hard to balance content.
* Make vit/str a 50/50 split. SE tried it. SE didn't like it.
* Put str on accessories. SE halfassed it. They put half the str on and scaled it miserably (1 per 10 ilvl) which doesn't actually solve the player problem. Tank accessories are instantly garbage and never used. Tanks still have the odd burden of having expensive pentameld be BIS for the entire ilvl tier unlike every other class.
* Put FULL str on accessories. SE hasn't tried because tank damage would be 'to damn high'.
So this 'convoluted' solution gives SE what they want. Separate damage and defense stats and keeps tank damage in check. It gives players what they want. More even power distribution between left and right side on par with other classes so tank accessories are actually worth equipping and don't make the raid facepalm when they drop, and stops the stupid system where expensive pentameld gear 20 ilvls lower is BIS. It makes tanks the same as everyone else while accounting for SE's self stated reasons why they wont do what players want.
All that besides, theres nothing really convoluted about it. Add the same str to all tank accs as on melee gear. Whatever % that raises damage, lower weapon damage across the board by that %. Its literally only making 2 gear number changes. No potency rebalancing. No revamping jobs. Changing numbers on gear by flat ratios. Its stupid easy.