There's nothing wrong with talking about true essences. When I described Yudkowsky's "step backward" into philosophy (and thinking about 'the true essence of intelligence'), I was speaking positively, of a behavior I endorse and want to see more of. My point was that progress toward engineering can exhibit a zigzagging pattern; I think we currently need more zags than zigs, but it's certainly possible that at some future date we'll be more zig-deprived than zag-deprived, and philosophy will get prioritized.