In my personal opinion and in a word, no. You need it if you are serious about digital photography as a pro or enthusiast.
Long ago when 35mm camera film ruled and digital camera's were a mere comic book fantasy, there were numerous factors beyond just the type of camera you were using and the photographers ability to use a camera that would determine how pictures would turn out. Obviously the type of camera, camera optics and your actual ability would have a significant/huge outcome on how your pictures would turn out. But you also had to decide on the type of film you wanted to use for the style of photography you were going to use with different speeds. There was also the myriad of different manufacturers of 35mm film that were said to have/actually had distinctive characteristics despite all of them developing film for the graded standards of film speed segments. Then after you'd taken your pictures (provided you'd done all you could within the bounds of your ability to achieve the snaps you wanted), the actual development process would also determine how the pictures would turn out too. In fact renowned famous photographers would also achieve their distinctive styles partly characterized by their personal tastes and methods of picture development in their own personal dark rooms. Then there were obviously the generic domestic high street stores that developed film for the general public which were geared toward developing film within a more generic way with less room for creative license as far as the potential results were concerned, and depending on which franchise chain you had it developed at there was more often then not a noticeable difference in how the pictures turned out when you went to collect them a few days or a week or so later. I remember how one particular high street photo processing chain would develop the pictures with a crisp sharpness and flatter colour dynamic to them and how another high street photo processing chain would develop them with a little more vibrancy if not slightly more colour saturation despite using the same brand and type of 35mm film roll. Even from a 35mm negative frame there was still quite a bit of scope to tweak the contrast, colour saturation, temperature and apply some under/over exposure correction, I'm sure they corrected as best they could many an unintentional botched effort on a 35mm frame into something a little more acceptable on 6x4 prints. 

Technically in this day and age the digital picture development happens instantly in your digital camera at the point of taking the picture, but its by no means complete in the fuller sense as far as the end user is concerned if you're a little more serious about your snaps. I reckon using Photoshop and/or Light room is like the part of film roll selection (only after you've actually taken the pictures) and the developments process, only there are no fiddly negatives to deal with anymore, and like the famous photographers who did it with 35mm film rolls, you now get to properly fully process/develop the pictures your own way and how you want it, at least in digital form anyway. (and without having to know anything about chemistry and the film to picture development process).  It’s the dark room moved on and digital with a boat load of other tools to help you achieve better pictures or the pictures you want. The only problem is a bunch of digital voyeurs will also be viewing uninvited too meaning that any kind of signature style won't be signature for long, especially with the digital encoding of all the setting you used with data about lighting condition to each image taken with a digital camera and smart lens. 

If you're looking to wet your feet (as its a little more on offer then what dipping your toe might entail) with some full on legit Adobe Photoshop antics in a relatively in depth way with everything you might need, but maybe aren't quite ready for full on CS5 or CS6 antics quite just yet you might want to try here.