csmith-norwood
I'm concerned that the "big customers" are the ones that asked for and like the changes.
Its Microsoft deciding they don't want to pay low-level developers to update and maintain Outlook, nothing more. It is a money decision. It could be updated with the necessary security and functionality improvements instead of this rewrite to the god-awful website and passing it off as the same. But by removing Outlook and only providing the website they can write the same website for every OS and the c suite get a lovely bonus at the customer's expense.
The deal with "its good enough" can be very easily applied to Open Office and Libre Office and the competition which is entirely good enough and best yet Free, we just don't yet have an Outlook competitor: yet unless Thunderbird is good enough for your must have requirements.