A while back I was reading some interviews with older famous programmers, like Dan Bricklin, author of Visicalc. Before the spreadsheet, everything was special-purpose. I think the reasons you give are a big part of why the spreadsheet was so valuable. That's not to say special-purpose business applications don't have a market, because obviously they do, but before building something like that I'd double- and triple-check that it's really better enough than a spreadsheet to be worthwhile.