There are many songs that are just as good recorded in the studio... Live just brings a different element into the equation... and typically, your ear is much more forgiving to the live experience... The Pet Sounds album would be very hard to duplicate live and Brian Wilson was using the best session musicians in LA at the time...
First of all: Hate me if you like. Consider this blasphemy if you like but I don't understand the hype over Pet Sounds.
I'd listen to Allman Brothers at Fillmore East on repeat for the rest of my life before I listened to Pet Sounds in its entirety one more time.