Of course, my take on this is heavily skewed because I am more of an engineering user of these tools than a typical office worker. And, although I have used it extensively for such things as invoices, purchase orders, financial calculation, presentations and business documents I still think of these tools as part of my engineering tool set.
Examples:
I devoted about three months to write an Excel VBA tool to help automate the creation of components for the EDA package we were using at the time. Creating a component such as a 1000+ pin FPGA went from almost literally days to an hour or two after this tool was in place.
Use Excel and the built-in Solver tool to find solutions for programming a clock synthesizer to output a given set of frequencies.
Use Excel + external voltage, current and temperature sensors to log and analyze test data.
Use Excel to easily produce and maintain lookup-table-driven state machine code in C, including all the callbacks for each state.
Use Excel to produce CNC G-code to run a Haas VF3-SS milling machine to produce patterned holes and threads.
Automate Powerpoint with VBA to simulate the control panel of a piece of equipment, complete with a small dot-matrix LCD display and functioning menu buttons. This was used to for training purposes when the actual piece of equipment was not available.
Use Word and VBA to automate parsing of documents and extraction of data.
Anyhow, just some examples that come to mind.
I had to install '07 when we switched to a Vista 64 to be able to run FEA and other tools that would benefit from that platform. I remember going from being a "power user" to feeling like an utter idiot. The UI change was brutal and I am still not sure that it was an improvement. They also modified automation and put in all of the roadblocks that just made it painful to use.
Office 2013? Nope. Thanks.