My take on Verant's philosophy:

Step 1: When you introduce something to the game, make it royally suck, in
the name of class balance, so no one will get pissed off about becoming
useless.
Step 2: Slowly make incremental improvements until the people who want the
change stop bitching a lot.
Step 3: Walk away for months to see if bitching continues.

Case Study: Rogue Poison
Step 1a: Royally sucks - Must become master at pottery. Must collect rare
drops from various low-level creatures (wasps, spiders, snakes). Make very
difficult to apply poison to blade. Only blade in primary slot can be
poisoned. Randomize when it will proc (if it does). If the rogue is
moving when procing, it is interrupted. Make it highly resistable by the
mob. Ungodly epensive.
Step 1b: No One Complains About Being Useless - Warriors do not bitch about
being outdamaged cause no one will ever see a poison actually work anyway...
Step 2: Make Incremental Improvements- Make it so poison will proc on first
stab and fix interruption bug.
Step 3: Walk away for months to see if bitching continues - (In progress)

Case Study: Aqua Lung
Step 1a: Royally sucks - Must be high level (40+) in order to build skill
up to a point to attempt to create aqua lung. Must be god awful expensive
to attempt (250pp+).
Step 1b: No One Complains About Being Useless - Make it a charge item (like
stalking probes) so that druids, shaman, etc., don't complain about losing
enduring breath.
Step 2: Make Incremental Improvements: Unknown at this time, but might
require some rare drop consumable (such as a decaying sharks left gill -
right gills won't work).
Step 3: Walk away (might skip step 2 and go directly here)

The same can be done for pretty much everything they've introduced. I don't
like it, but I live with it.