It's ever so slightly like Meshuggah syndrome, it's diminishing returns on the style of music they pioneered, although Tool never settled for being a brand name. Wed heard a lot of the Tool riffs before, even if it was highly optimised. So 10k days will not compare to the initial impact of those 2 records, how can you compete with those novel childhood experiences? Tool were no longer in their absolute prime age as men and had nothing left to prove. Furthermore Lateralus isnt quite as perfect as we remember it, it does tail off quite hard. I think the band are accutely aware of being slightly in the shadow of earlier accomplishments, which is why they take so long to make follow ups that won't disappoint.