Or...They just write what they want to and aren't thinking ''this will get us a lot more fans if we write the songs like this''. Just look at the bands the members of IF listens to nowadays. Also they grew tired and bored of writing the same shit that is why they experimented and tried new stuff over the years, imagine the Colony album without the samples and drum loops, it added a new flavour to many songs and made them better imo. The title track is a good example.
I remember reading and interview with Fredrik Nordström from maybe 10years back and he said
''Around the third album, they wanted to stop using the melodic guitar harmonies. I was the guy saying, no, no, we have to keep the melodies. We have to do the harmonies. No! We are so bored of harmonies! (Nordström now takes an authoritarian tone) You have a responsibility to your fans! And they are expecting this stuff."
But I don't agree about the ''responsibility'' thing at all. Bands should be able to write whatever they want, if people like it nor not that's not their fault, they shouldn't cater to peoples opinions and write music they don't like themselves.
You are right that they COULD go back to their roots, but they do not want to, and it would not sound as good anyway. They've already done The Jester Race and Whoracle, why do it again? Maybe for some like you, the newer albums suck, but for me, I love them as much as I love all the old albums. I mean two of my favorite IF songs are Stand Ablaze and Fear Is The Weakness...They are on two different sides of the spectrum, music wise, but I still love both of them.