These albums might have have been ground-breaking at the time but over time through overplay and being churned out on the likes of "Smooth Radio" etc they lose potency. As always, context is key and you have to think about the time and place that these albums were made.
If you listen to music before an album like "Pet Sounds" and music after it, it's striking. It helped to create the idea that an album isn't just 12 singles put together, they should tell a story and it is one of the first concept albums. The vocals, musicianship and production on it is sublime. To create that sound and harmonies - regardless of era - is something else.
Whilst Good Vibrations isn't on the album, I'd say that it easily ranks as one of the finest pop songs ever written and one of the most important pieces of music of the 20th Century - regardless of genre. It literally is one of the first songs that could only be created in a studio. It is one of the songs that signposts music away from the 'simple' pop songs of the 50s and 60s and points musicians to a level of complexity that was previously unheard.
Good Vibrations and Pet Sounds were also hugely influential and it pushed The Beatles to go and make Sgt Pepper which is arguably the most influential rock album made. Without Pet Sounds, pop/rock music wouldn't be the same - it's as simple as that. I'd also add that, quite simply, just 2 or 3 years earlier it wasn't something you could imagine - it literally was groundbreaking.
That said, 60 years later it sounds dated maybe (I love it) but like any artwork, without the context you hear it as a collection of songs and tunes. Without question, it's a hugely important album though. Imagine hearing it for the first time in the mid-60s.
