The other thing to remember is that all the stuff about bidline, seniority and other opportunites in a company like BA (management, training, sim panel operators, pilot-ambasadors etc) means that you can have a developing career. As you develop seniority you get more choices, you have different fleets and oportunities etc.
Seniority has its detractors but probably mostly amongst junior guys - although I'm the most junior on my fleet and one of the most junior in the company as I only joined a month or so back, but I can see the future benefits in the system, but to be honest even a blindline of junior work is still head and sholders above my previous job with random rostering to the limits (and beyond) of the law and massive roster disruption.
Maybe some people prefer the 'equality' of an low cost airline fixed roster pattern etc - and I'm sure its great for some - but where is the career development, the change and improvement over time? day 1 ezy - heres your 5-4-5-3 (or whatever it is) - and this is what you will still be doing in 40 years time - I'm sure it can be a great job but I don't call that a career. BA I certainly call a career