I use my current Macbook (2008!) for surfing the web, Word, iTunes and barely Garageband and once every 2 months dowloading a movie off iTunes. I'm a pretty light user, no huge software and not programming music or editing videos, nor do I foresee this.

Instead of spending over $2k on a new Macbook Pro, I'm considering buying an iPad.

Am I missing something or would buying a 32GB iPad suffice for what I use my Macbook for? The most memory is used for is my MP3s which I'd still keep on my Macbook anyway.

Any thoughts why I shouldn't just get an iPad?

Going by what you have listed as your usage, an iPad would most definitely suffice. There are obvious benefits to an iPad; battery life, weight, size, battery life. Of course you don't have to spend 2k to get into a Macbook, you can pick up a MBA for under 1k, check out the refurbished section of the Apple store.

You can always try out an iPad, if it doesn't work out after a few months, just sell it.

The MacBook Pro is not the only computer to compare with. If you want similar size to the iPad, you should look at the MBA 11". Super small, fast and give you the desktop needs. Both will do what you need to do in the end, just one with iOS and the other with a full version of OS X