We could play this game with almost every product... I am sure there are many things that you use and like to use that I never use, but it isn't fair for me to just say, "Well it isn't important to me so that means it isn't important to anyone". Almost every product we produce, people could 'manage just fine' without... we can always just point to a time before the thing was invented and say, "Look, people managed just fine without computers... they aren't a necessity, let's not waste resources making them" Unless a product has outsized environmental costs relative to other luxury items, I don't think we should get in the habit of having governments pick and choose which items are 'necessity' or 'luxury'.
If we are concerned about plastic waste, let's put a general tax on plastics to reduce their consumption across the board and let the market decide how to do that reduction, instead of picking and choosing which plastic products to ban.
While I don't think people need to justify using straws, I will go ahead and say straws are very important to me. I like cold drinks with ice in them, but I have cold sensitive teeth that hurt when I drink from a cup with ice and no straw. It is way easier to drink in a car with a cup, lid, and straw.
I simply prefer using a straw. Do you want to go through a similar exercise where you justify every single one of your consumption practices?