I completely disagree with this idea Abacab resulted from their sitting down and consciously deciding to capitalise on PC's solo success and/or "we'd better sound more modern and new-wavey". Both are silly notions. They didn't want to repeat themselves, simple as that and absolutely right too.
Genesis wasn’t alone in that respect.
There seemed to be a widespread movement among prog bands at that point to leave the ‘70s sounds behind and produce music that was leaner and more contemporary sounding.
Gentle Giant, Camel, Yes, Rush, Jethro Tull — even Steve Hackett — all adopted, in some circumstances, quite radical changes in their sound.
Genesis, Rush and Yes ended up drawing bigger audiences as a result.
The others I mentioned did more to alienate their traditional fan base IMO, than to build on it.