For me it's all about internet availability.
That's why I need a lot of space on my iPhone and not a lot on my iPad.
Why? Because I cannot guarantee I'll always have internet access on my iPhone so I need to store music, photos, videos and so on offline.
With my iPad I know that I am only ever going to use it when I have a Wi-Fi connection and this means I can download everything I need on demand. Hence I can get by with a 32GB iPad very easily.
So, if you embrace iCloud and other off-device storage services and know that you will have internet access nearly all the time, and you don't expect to be taking lots of high resolution video or installing big apps, definitely go for the 32GB model.
Just my opinion. Most people here have quite a strong aversion to the lowest capacity models so I will probably be in the minority.