Was Open Source such a good idea after all?

Whilst I'm not a great fan of open source I can see the appeal and it works well under most circumstances. Some of the objections you raise would be the same at a commercial company; people leave, business needs change, technology changes so there is never a guarantee that what you buy today will be usable tomorrow, so to speak. Same goes with Open Source but without the initial cost.

However, there is a 'total cost of ownership' related to any product so, even though the open source product may appear to be free, in reality there are ongoing support costs.

This is true of any product regardless of the initial cost or licensing criteria: business has to decide how it wishes to pay for product and what levels of support are required to keep employees working. Very often this is easier to do with a large behemoth like Microsoft or other commercial companies and products and more difficult with Linux or any other of the myriad open source products.

Bottom line: there is no simple answer: a business has to hope that it has employees who make the right technical buying decisions for their business and that the products they choose are supportable and cost effective across the business life cycle and adequately cover business needs.

My experience is that all of the investment and retail banks I have worked for have, primarily, chosen Microsoft and not a single one has used open source (or Apple) other than for the odd specialised application. I'm not saying they are 100% correct for taking this position but they made those decisions based on cost and ease of use. Whilst there are many that deride Microsoft, they make very usable software which fits into the business cycle very simply. Open source still appears to be lacking and until they catch up the answer may well continue to be Microsoft (commercial) as opposed to to Open Source (free?).