Noone promised you an 'urf holiday'. It was something that came out of the blue two years ago, and they brought it back last year as a joke mostly because it made a nice punchline for the NURF videos and jokes they made, but that's it. It's not a lol holiday. It was a one off gag that was brought back exactly one time as the punchline for a different joke. It's not coming this or any other April first for now on.
What you are getting is it and a bunch of other features game modes in a rotating queue. You will be getting the mode you apparently can't live without far more often on average in the rotating mode anyway, plus there will be breaks in between so that the super tryhard metas take longer to go into effect and you can actually enjoy your urf for longer instead of paying it for 3 days straight and then abandoning it the rest of the two weeks because it got old or people found the broken stuff and drained the fun out of it.
That's what the data from 2 years says by the way, people play features game modes in significant quantities for about three days and then it drops off hard.