any chance of complimentary drinks etc, which seemed to be a firm “no” - I guess practically difficult but it feels like the kind of thing that would go a long way in retaining customer loyalty.
That kind of feels different to the lounge, but it may be a nuance. The difficulty would perhaps be anyone else in ET who felt that they should get a drink and if there were a lot of people downgraded, then it rapidly gets quite tricky. There would be Golds and GGLs thinking "why are they getting extra drinks?". For lounge access, it's between you and the lounge agent, no-one else needs to know. If you were cancelled then you can claim reasonablle refreshments under Right to Care, so you could just buy them and charge it back to BA. But as you rightly indicated, you were travelling for a reason and you ended up where you needed to be, so maybe this is a detail.