I've seen the suggestion a few times in the Kongregate comments to change the scoring to be based on "total tools used", rather than requiring specific tools to be used. I wanted to share my thought process on that to shed some light on why I ultimately went the way I did. This was absolutely a design consideration when making Episode 2, and a good one at that, but ultimately, not the best approach in my opinion.
In its original form, Episode 2 worked similar to Episode 1. The player was only given enough tools to complete each room. I wanted to make the game more accessible to players of all skill and dedication levels, so I needed a technique to make it possible to complete rooms at an easier level.
Adding in extra tools was done to create many more possible solutions. The key point here is that adding more tools makes the room easier to solve. A gold star is more challenging because there is only 1 solution, maybe 2 if you discover a platinum solution, because you are given very specific tools to use.
The suggestion to be able to use any breakdown of tools would make it much easier to achieve Gold. There were many instances when crafting rooms that I knew that having just one more loot bag would make a room's solution infinitely easier. Again, in its original form, you wouldn't even have those extra tools, so if you play the game with this mindset, you won't even consider going beyond the Gold level's tool placement restrictions.
I hope this helps understand my logic.