My pet theory is that people have a love of grids and graph paper -- I remember in grade school how graph paper was, for some reason, a rare thing, and it was treasured. The kid with a whole stack of graph paper and who DREW PICTURES OF TANKS AND DRAGONS ON IT was considered some kind of blasphemous rouge, but still respected because of access to graph paper. It brought some indication of order to the otherwise sloppy handwriting on looseleaf we had to do.
And that love of the grid translated into a love of spreadsheets. It's so neat and clean, ready to be filled up with MY organized madness! All those empty boxes, what fun! Look, I made a list of items! And it's arranged in neat rows and columns! And besides, who needs to be able to join these product ids with sales numbers? We can do that with a hundred clicks or so and create a pivot table!
Everything begins to look like a nail when your hammer of choice is Excel.