This came out in Japan last year and no, it didn't because it is a low effort port of an expanded edition of a stop-gap title that was composed almost entirely of remixed content from old games.
While you are correct about it not outselling World, your reasoning is fairly off. It came out last August when there was only a few million Switches out there. Switch was selling out routinely so there was no chance Monster Hunter could boost sales. Lastly, it came out on 3DS as well in Japan. This fact alone ensured the sales would be limited as there are over 20 million 3DS users in Japan who would have 0 incentive to try fighting for a Switch to play Monster Hunter at that point.
The game has reviewed well and was received well in Japan. That tells me that you were just trolling with those comments. With all that said, I completely understand how the quality of life improvements and graphical upgrades will make going back to Monster Hunter on handheld seem like a terrible idea. I am one of the few people with the ability to go back to Generations Ultimate because I see it as the handheld version vs the full console version being on PC (or PS4/XBOX One). However, people that are looking for the comparable console experience from Generations Ultimate are likely going to be disappointed.
01000110 01101111 01110010 00100000 01001001 01111001 01101111 01101100 01100001 01101000 00100001 00100000 01000110 01101111 01110010 00100000 01000101 01110100 01100101 01110010 01101110 01101001 01110100 01111001 00100001 00100000