I'll conveniently leave pensions and pay out of the debate (the pensions change was wrong but I'll leave it to others to debate the ins and outs of it because I can't remember the details).but otherwise I'm not convinced it's as polarised as you are making out.
I've been very senior as a P2 and am fairly senior as a "P1" - until I went part time even as a top band Long Haul P1 I did Longhaul reserve probably once every 18months (some was down to bidding, due in parts to the points system) certainly still worked and continue to work during school holidays (again in part the points system) and have worked, mainly by choice, the vast majority of my Christmases- and again, there's a points system to prevent someone permanently avoiding working over the festive period. FWIW the aspirational part timers are pretty much forced into weekend working in their Part Time months by virtue of the hotspots, regardless of seniority.
There's a gradient, sure, whether it is too steep or not is rightly up for debate and has been forever, but it has flattened over the years. I can't speak for Short Haul roster patterns but as far as Long Haul goes anyone thinking that BA junior Long Haul pilots just do all the *****ty work while the senior pilots work 7AM to 5 pm, weekdays only, only do beach trips, never do reserve and never work over a holiday is just a bit wide of the mark....