[sanxiyn]

Well, handicap also destroys Go's standard opening theory, which is very extensive. (Start with 4-volume Dictionary of Basic Fuseki: while far from comprehensive, it covers basics well.)

But! Handicap is common enough in Go that there is opening theory for handicapped games! This may not apply to Chess directly, but my point is that if handicap is a normal part of the game, you will have opening theory for handicapped games. This is kind of obvious if you think about it.

[mst]

I've always loved handicap systems in any game; if I'm playing a stronger player in a game that doesn't have one, I set my own mental victory bar as 'lose less badly than previously'.

I suspect it's a psychological function of valuing absolute victory over valuing progress in your abilities, and which of the two you consider more important - and while this is entirely subjective, I feel like Go plays better to the latter set of values and Chess to the former.