How much time do you want to spend in Post Process and how much time do you want to spend learning how to use the Post Processing software and what to do with it?

For most non-professionals/very enthusiastic amateurs too much time is required to learn how to use Photoshop. Yes it's powerful. Yes there are some things that it can do that others can't. But it's like the BMW many SLR owners drive around - it spends 99% of its life doing the exact same thing as a Honda, just as well, but at 2x the price.

Lightroom is a program that simplifies the back end work of managing your photos, basic editing, and in general makes taking photos more fun, imho. It's also cheaper.

There are other programs out there, but Adobe is the standard. Nikon Capture is a waste of money.