I believe the foregoing are compelling justifications for choosing Excel Visual Basic over Visual Basic.
It's not enough to have a professional with the technical skills to solve your problem. s/he also needs to have the right attitude and background/experience _ else the relationship will not work. This is where an Excel VB resource is more likely to add value to you. Most Excel VB Developers have backgrounds in management, accounting, engineering and other fields, which further equips them to be useful to you in "thinking up" better ways to apply your spreadsheet automation to get the most value for your business. You therefore need to choose the right developer, with the appropriate background to match your needs.
For the purpose of creating custom financial and business management solutions that solve your identified problems, and give you control/ownership, without burning a hole in your pocket, Excel VB offers an amazing variety of possibilities, in the hands of an adequately skilled user.
The savings _ from using your "in house" expertise _ in terms of money and man_hours alone, will quickly justify the investment you make in "developing the needed skills" _ especially, when you compare what you spend with the cost of purchasing a commercial software application _ or even engaging the services of an Excel VB developer.