The reason why it seems blocky is the PenTile Matrix display with the sub pixels..aka you have less effective pixels...this in turn saves battery life
This is a reglar AMOLED..not Super AMOLED but similar concept:
that said you generally would not notice it unless you look REALLY closely...
That said I do not see a reason to want more resolution on the EVO...the resolution is ok...it actually is missing A LOT of colors...if you look at gradients they look completely unnatural...
I think if anything Super AMOLED needs more resolution to be perfect..sub pixels are not that bad if you consider the fact that even the creator of square pixels criticized their existence...