Huh, I wasn't aware you were part of their development team as a coder, with intricate knowledge of their gear coding to be able to even comment on the simplicity of the action. Silly me!
Sarcasm aside, you can't really comment on the difficulty of something like that. Regardless if you want to consider it lazy development, or just realistically using your resources it doesn't change the fact that the chances are very high the next tank job (if there is a next tank job) it will continue to use Fending armor. Of the two tanks proposed (RMD or SAM) Samurai is the one with the most history of wearing heavy armor and is thus the more likely option. It also has plenty of other common features with the other tanks which while not providing more diversity offers up an easier time balancing which again is the more likely option they will take.
These things have been discussed before and ultimately with these solutions, how would this job be any different then PLD and DRK? They have instant cast (And some cast time) spells. DRK manages MP as a prominent mechanic. You would have a melee attacking job with instant cast magic spells, which just isn't that much different than what we've already got.
Because people are selfish and want the role that they play most. More players play DPS jobs = more people ask for it to be a DPS. Doesn't change that adding tank roles and healing roles are far more important to the health of this game then a constant stream of DPS jobs.
My point is between these 2 very requested jobs, one of them fits as a tanking role far more easily than the other. Easier = more likely to happen when time and money are factored into the equation.
They're also responsible for putting out buckets of content every 3 months. Call them lazy all you want but there isn't another MMO on the market that pushes content like they do.
I would love for them to have infinite freedom to make whatever their wildest imaginations can think of, but at the same time the reality situation is they are only human, they are a business, they have time and budget constraints. It's fun to think of all kinds of wild and crazy ideas but in the end things need to be grounded.