While I can understand that for many people 32GB internal storage is plenty, it isn't for me. I'm probably unusual but I like big, high-quality files often of unusual content that not currently available for streaming. Almost all of my audio files are FLAC... meaning real big, 20-25 MB each track. I abhor lossy compression.
I also love high-quality video files. I can't wait to watch my 720p mkv files on that SAMOLED HD screen (assuming the Galaxy Nexus support hardware mkv playback.) Unfortunately, they are huge... like from 2 - 3 GB for each file. A whole season of a TV show and you're maxed out on 32GB. I look forward to adding huge microsdxc cards (>128 GB) to my future phone(s). I don't want to have to depend on the "cloud" for these kinds of files. Stream one such show off the cloud (if it even supports that high of data rate) would bust the cap on the Verizon's new $30 2GB data plan. Really expensive way to watch a TV show, isn't it?
Until the data plans become more generous and less expensive, external sd card is something that I'll want to have on a phone. Of course, these are my needs. Everyone will have their own situation but for me external sdcard is a pretty important option.