BAEC still has value, definitely. But if you don't have BAEC then you can forget it, which wouldn't really encourage new people to use the carrier. That said, looking after your regulars is the first thing in business, and BA do manage that.
I used to have gold guest list on BA, but after a poor flight to Sydney in First I started looking elsewhere. Qatar in business and Finn Air in business was so much better than BA in first, and about half the price of BA in business.
One trip I did to Sydney
Finnair business Manchester to Helsinki (An embraer, but the flight and service was far better than the domestic flight to Heathrow on BA)
Lounge in Helsinki better than at Heathrow (as gold I had access to both Helsinki and Heathrow first class lounges)
Finnair Business to Singapore, better than BA business, and service was better than BA in first.
BA Business to Sydney.
On the return BA even upgraded me from Business to First as far as Singapore.
The price for this was less than BA in premium economy.
My experience of BA as a frequent flyer was everything going down hill through penny pinching, but it was the lack of apology over the snooty purser breaking their own rules and making my family less safe (she clearly didn't like having a 9 month old in the front cabin and insisted he travel in our lap rather than on the seat we'd bought for him) that was the final straw.
I'm sure they didn't miss my £30k a year, but it felt good.
(of course with covid I haven't actually flown since March - had two trips in March cancelled - one by Cyprus immigration, one by US immigration)