I want to vote your post insightful and awesome, but it only lets me pick one! O_O

There is a cap on the inspiration that you can gain from a single deconstruction, and this cap is scaled to your current level in that craft.

This is the reason why an intricate item will yield the same inspiration as a regular item for a character whose crafting level is low, and this is the reason why people who want to maximize inspiration should save max-level intricate items for the later levels.

So it looks like the problem here is that the cap is not being updated with each level that you gain. If you separately deconstruct 10 items that take you from level 20 to level 22, some of those items will yield inspiration based on the level 20 cap, some will yield based on the level 21 cap, and some will yield based on the level 22 cap. But if you mass-deconstruct those items, all of them will be subject to the level 20 cap.

If you are deconstructing items that are yielding their full inspiration (i.e., the inspiration gain is below the cap for your current level), then it shouldn't matter if you single-deconstruct or if you mass deconstruct. For example, if you are at enchanting level 10 and you have 100 white-quality CP160 glyphs, you can mass-deconstruct them without penalty because at level 10, your inspiration cap already exceeds the yield from white glyphs (but not for CP160 purples).

If you mass-deconstruct in small batches--just enough to get you to the next crafting level and thus the next cap--then the results should be the same as individual deconstruction.