Hi Like,
There are some that will say that it will generate a little forward bite, although I think its very marginal feel if any. Your last summation is correct as the shock works on 2 dimensional plains. How much is too much though?
I space my shocks out mainly because a lot of time without a spacer they are tight to the shock tower and the shock has very little if any "twist" to it. I like to have as much of the suspension float as possible to eliminate any binding issues. JMO