You don't need a floppy to install XP. But you might need a floppy to install SATA/RAID drives that came with your MOBO.
A floppy drive costs $8.00 doesn't use hardly any power, most cases have a 3.5 slot. I always put one in my PC's, I know they are really obsolete but, there have been times when I really needed one and didn't have one. That sucks.
If I don't use it, Oh well, at least that one time when I do, it's there.