Having finished the game, I can tell you that those are simply some "nice to have" upgrades. None of them are actually necessary to finish the game. They can make some situations a bit easier, but that's all.
The one which creates a fluoro ensures you use just what you need of liquid, it prevents wasting. It also allows you to actually propel a fluoro where you want.
The big one is useful when you want to refill your container faster. It's also helping you to clear some areas (ie. lava belts) faster. Same goes for the one throwing orbs of liquid.
The blowback nozzle allows you to hover a bit, but not much more, even fully upgraded. It can help preventing you from falling in some endless abyss, or in spikes, lava, though.
All in all, they are just giving you little helps, depending on the situation. But you can make it through the whole game with the initial nozzle, as far as I experienced.