Do you NEED power steering? Do you NEED an automatic transmission? Do you NEED a high speed internet connection? Probably not, but they sure are nice when you have them.
If you get a hydraulic thumb, the uses expand. No, you don't NEED a hydraulic thumb

, but once you have it...
One thing about rental units, You will spend about 1/4 to 1/2 of the time learning how to use it productively. That will just about always be the case, unless you rent often. You will also be hurrying to get done in the time allotted and that's when boo-boo's occur. Like digging the power line up, or the gas line or the phone line, or...
If you can afford it, it ain't a bad thing to have. I would look for a non-JD unit to save $$. Heck,
1* for 12k you can probably find a used TLB.
jb