I will comment your point about overuse. I don't think that Excel being overused in companies usually refer to excel VS its spreadsheet competitors. The free alternatives are good to know, but sticking with Excel hardly constitutes a "misuse" in that regard.
I believe that most common misuses of Excel are rather using it to do things where a spreadsheet does not scale well, or is not the right tool for the job, including (and I've seen it all):
- Large databases
- Complex data manipulation, charting and reporting
- Automated systems, application development
- Brainstorming, mind-mapping
- Word processing, protected forms
- Multi-user, shared information repositories
- Task management, project management, budget management
- Mission-critical data
Often such activities are started with excel (or any spreadsheet), and that is fine, but a think the term "overuse" most often arise when it's kept growing past beyond the point of productivity/flexibility/cost-effectiveness. Solutions will vary per type of usage.