Hypermodernism goes beyond openings. You can't label a game as hypermodern or classical based on their opening moves. An e4 game may be played in a hypermodern way (prophylaxis, blockade, etc.). Karpov may start a game with d4, but he plays in a hypermodern way (being prophylactic and all). The same goes with Petrosian, who was influenced by Nimzo. Hypermodernism was a complete system designed to challenge Tarrasch's dogma. Nowadays it doesn't matter anymore as people just use whatever that works.
so... why is the OP thinking that it was unpopular?
Hypermodernism goes beyond openings. You can't label a game as hypermodern or classical based on their opening moves. An e4 game may be played in a hypermodern way (prophylaxis, blockade, etc.). Karpov may start a game with d4, but he plays in a hypermodern way (being prophylactic and all). The same goes with Petrosian, who was influenced by Nimzo. Hypermodernism was a complete system designed to challenge Tarrasch's dogma. Nowadays it doesn't matter anymore as people just use whatever that works.