As has been said, some cash fares are obscene at the moment.

Last month I went to Munich in CE and got about 8p value per Avios. If I'd gone in Y, it'd still have been about 5p.

I have an open jaw ex-EU in October where I return into Madrid. I wanted to book the B2B, but the cash price - in Y - was approaching £500. (I could have chanced a longer layover and travelled with IB for much less, but then I would have needed a London hotel room as I wouldn't have been able to get home.) There was Avios availability in Y, which worked out - iirc - at something like 12p value per Avios. I think that's probably the highest I've ever redeemed at.

Both of these maximised (or nearly maximised) the cash/Avios mix to close to the original RFS numbers.

So yes, there's certainly often compelling reasons to use Avios within Europe, particularly given the surcharges on long-haul and the cost of ex-EU itineraries if picked up at the right time.