I have a few straight needles in short lengths (10 inches), but I could live without them very easily. Circulars are much more versatile. With flexible cabled, pretty long ones you can do small projects via magic loop and flat things of any length on the short end and as big a project as you can comfortably get stitches on the needle.
Some folks like long straight needles, but I'm not one of them. I have some, but they reside in the bottom of my needle satchel. I think that many people who use them knit by holding a needle under their arm or propping it somehow. If you don't do those things you probably don't need them.
There are some cute straights. I saw some with little elephants, frogs, etc. on the ends. Cute but not cost effective for me. Most of the straights I've picked up are from second hand store finds.