Yes! Excellent, excellent point. The industrial revolution put a whole raft of the "easiest" inventions within a century's reach. Internal combustion, electricity, telegraphy, etc., these were waiting for just a few pieces of basic core technology (like coke-fired smelting)) to fall into place before they could erupt into mass deployment.

It makes perfect sense that refinement of existing technology would overtake invention of new ones. I don't see how it could be otherwise given the physical constraints you speak of; how many radical new sources of energy can we come up with, aside from fusion?