I used to be as critical as anyone regarding the day one tests. I failed them back when I was in my late teens when applying for the old sponsorship and then again in 2014 and genuinely believed I just couldn't make the grade in these tests. Nothing could be further from the truth. I sat them again last year and passed with flying colours (ahem). The key is preparation.
Instead of moaning relentlessly about them (and I was as guilty of that as anyone) why not just bust a gut in order to achieve the grade? Nothing comes easy and if you really want to work for BA then you must accept it might take some effort, I have a strong belief that that's a large part of what they want to see from you during the selection procedure. I did my sim assessment with a guy who very obviously hadn't learned the profiles and pitch/power settings they sent us. How do you think that comes across to an examiner? Needless to say he failed the sim.
If you're a commercial pilot worth your salt then you CAN pass them it just takes prep. BA obviously have a specific reason for using them otherwise they wouldn't exist. Good luck to everyone applying.