Rampant Rambling
My little GSI/ESI theory:
Your chance of getting an ESI declines the lower the mob's level is compared to the skill levels associated with the weapon you used for the kill.
It's just speculation, of course, but my favorite example is how I used to spend hours sitting in that big spawn of mid-upper level Tantillions west of PVP2 skilling LWT/HG skills without ever seeing a gsi/esi, but when I switched to finishing the tants off with low skilled (L) weapons like a smacker 3, I started getting the occasional ESI. At around 8K LWT & 6.5K HG, I rarely get any ESIs from pistol kills on mobs lower leveled than formidons, neconus, or Atrox Dominants...
So, bringing the focus back to the topic of the thread: I don't think the chance for ESI drops has increased, but I think the number of lower skilled players hunting higher level mobs (thanks to (L) weapons & faps) is rapidly increasing. Therefore, the overall number of ESIs appearing on the market should increase for the nearterm (longterm?) future.