I can understand that airlines are trying to hang on to as much as they can however from a customer point of view if you've paid money and they are no longer providing the service you have paid for then they should be refunding, no question. I think it's perfectly fine to offer a voucher but people should not be forced to accept it.
However what does seem stupid is to make it impossible to get a refund on their website (as BA are doing) and insisting you call. Then they complain that their call centre is really busy, running on reduced staff etc. That's hardly surprising if you're going to force everyone that wants a refund to call rather than be able to do it on the website.
The problem I have is that all of the airline information I have seen is deliberately steering people towards accepting a rebooking or a voucher, and I have not seen any information from any of them clearly stating the legal position that a full refund is a requirement if the traveller wants it (for all cancelled flights originating in the EU). The wording is deliberately vague, and, as you say, the Web sites don't enable you to collect the refund to which you are entitled.
This is, essentially, a business which uses technology to extract money quickly from people in the first place, but won't use the same technology to return their money to them as the law mandates.
I am fortunate in that I will remember these actions and take action against the worst culprits in the future, but I fear that many future customers will have short memories, or are restricted by a semi-monopoly carrier at their local airport.
My mantra has always been to under-promise and over-deliver, and that a company's actions when things go wrong are what define it best. The airlines, collectively, have not scored well in my opinion in recent weeks.