As someone who loves skills on release (reached 120 in the top 100ish of Invention) I was really looking forward to crushing out Archaeology and gaining some levels again, but I am happy it got delayed.
Invention was an unmitigated disaster, at first training the skill by weapons was so freaking slow, a level 10 weapon disassembled into 30,000 xp with the weapons + augmentor costing an exorbitant amount of GP for the experience it gained. It was cheaper and faster to just dissasemble random items instead of leveling items, let alone the OP xp rates from gizmos.
The players complained and they changed the skill, they gave a 1800%, yes that big, of an XP boost to the gear you were using. This meant leveling was the new meta and you could get over ~1m xp/hr just killing random slayer mobs. I personally did Muspah's with Gano (d/a) and a Nox Staff (siphon).
To this day invention is pretty unbalanced for the xp/hr you are getting, this is evidenced by the fact that ~1/16 people who have unlocked invention have 200m in the skill and over half have 99.
Now the delay will allow the J-Mods to play out certain parts, see if its frustrating to do certain things, whether you do a method for too long or too little, etc.... All these sorts of things that you don't experience when playing on an accelerated server or spawning in items. Hopefully this will lead to a smoother release and a more fun experience