Going by that logic, Colony-Whoracle-TJR should be more popular than Clayman because they are out longer.
And there are different types of "heavy"... Most people observe Death as heavier music than Slipknot, Korn, Drowning pool (is that the name) etc... For me, it is much easier to listen Death then any of those bands. STYE is heavier than Claymen sound wise. Less melody, guitar sound is uglier, even Anders screams are more aggressive sometimes... BUT (and that's a big but) STYE is not heavier ideology wise. It is written in very pop-ish, easy to consume way compared to Clayman (not to mention earlier albums). "In the US it is popular to scream about suicide and hate and do chugging riffs, so let's do it."
In Flames started to write songs that are just "speeding things up to get to the first catchy chorus", and because of that their music has became shallow and one dimensional. From all these albums RTR-ASOP there are no epic riffs that will became legendary, there is no real aggression and purpose, there are no new, progressive ideas, no dream-like passages...there are just catchy choruses and a few memorable melodies. Songs started to revolve around choruses like satellites around planets.
And I hate that. I hate nu metal, metalcore, glam rock, pop...and a I love prog rock, death metal, thrash metal, NWOBHM, even some avantgarde black metal, classical, folk/etno music, trance etc... TJR-Clayman belongs into music I like, R2R-ASOP is in the group I dislike.
It is the same band, but music is not the same. And I don't care, they can write Lady Gaga-like songs if they want to attract wider audience, but I don't have to like it.