As long as that data is decode-able and more importantly, find-able (out of all the GBs frozen for 100 years, why would you want to look at any particular one of them?).
I'd store my pictures there. Finding old pictures of grandparents when they were little, or even older stuff, is amazing. Wouldn't it be cool if my descendants could still look at pictures of my family in 100 years?
Provided that downloading from this 100 year store is something I could do X times per year, and so long as I could append more data to it over time, it's an interesting business model.
But that's from when it was harder to make and upload data, so people only put meaningful (to them) stuff online. These days we'd have a hundred thousand copies of a few popular MP3's and everyone's crappy digital photos. The percentage of meaningful stuff would be a lot lower.