Console games have a $60 MSRP, portable games have a $40 MSRP. Only a fool would expect the cheaper portable to offer the same performance with a smaller market, hardware limited by batteries and ergonomics, and a lower price-point. It just doesn't work that way.
And this is coming from someone who spends more time with his PSP than the rest of his consoles combined.
Most developers don't put a ton of effort into portable games because gamers don't financially expect them to.