End game if you look at the Kite shield for PLD, it's the same for block rate and block strength, so if an enemy attacks at a constant rate there is a breakpoint, but at lower damage points...
Now imagine if an enemy hits very fast but for lower damage, in which case the high block rate would be better.
Vice versa, if you are against something like Titan that hits hard and slow, ideally you want higher block strength, but at endgame I'd argue it matters less since each has it's trade off.
The reason we have kites is tradeoffs aside, if you're gonna have 1 good shield it ought to be balanced.
Edited, Sep 24th 2013 1:46am by SyniteonReflux