I'm seeing a lot of hate for spreadsheets here.
First, to state the obvious: in the time your least-favourite Excel sheet took to grow from simple time-saver to sprawling Cthuloid monster, it has probably saved multiple person-years of effort. You could spend the next six months rebuilding it all "properly", and it's still comically positive ROI.
Spreadsheets are also a unique, top-level category in computing as a whole. By my count, there have only ever been three schemes of interaction with computers (with any significant adoption):
1. Shrink-wrap. Use the software you've been given. Read the manual; that's what it does, no more.
2. Programming language. It's text, it's got syntax, it's got the same basic constructs as any other programming language. You know they're all the same, because once you know a few languages, you can start using a new one in an hour or two.
3. Spreadsheets. Visual interaction, scaling smoothly from "simple calculator" to "this is the backbone of our whole business".
Spreadsheets really are that fundamental a discovery in the field of computing. Give them some love.