That sounds like a shift for the worse that doesnt add anything significantly different while borking the early game. I don't know if you've played the pikmin series, but they're already pretty open in terms of what objectives you can tackle in any given area. The only major shift would be acquiring pikmin types out of order, but that would just destroy a lot of the early difficulty of the game when you have to think around your limitations, you could just grab the pikmin you need early and roll over the puzzles. Pikmin being "open world" wouldnt make much difference either. Olimar is sloooow, you would be heading to your ship to fast travel more often than not, which segments the world into chunks anyway. The game isn't designed for being totally disconnected from the hub ship/Onions, you still would need to return to them frequently, cutting down wandering and openness.
If you want to make pikmin popular no matter the cost to difficulty, the obvious solution is to get rid of the time of day mechanic and let you wander unrestricted for as long as you like. Then you dont feel any pressure and the game isnt breathing down your neck about what to do when, giving the starting player ample time to learn.
If you want to make pikmin popular no matter the cost to difficulty, the obvious solution is to get rid of the time of day mechanic and let you wander unrestricted for as long as you like. Then you dont feel any pressure and the game isnt breathing down your neck about what to do when, giving the starting player ample time to learn.