I really don't see how "just accepting a decision and moving on" is a good and healthy way to live in this world. As with all things, it really depends on the situation. I don't think being inquisitive and sort of a cynic is by no means a negative thing. Obviously this case the OP describes is a bit different as they're considering legal action (I presume that is what is meant 'taking it further'), but generally speaking, I'd always encourage people to question things, demand answers etc. You may not always get it, but more often than not, you'll realise people can't slip one past you and take you for a mug.
As an example, a young lad, many moons ago, worked an office job on about £21k when management began expanding his team - all his new teammates, doing exactly the same job as he was, were brought in on £24.5k. He took it up with his manager who told him he couldn't get a raise because 21k was the going rate when he was hired and the circumstances are now different. He accepted it, and kept to himself for another year or so, still earning less wages than all of his colleagues, until someone suggested to him that he should put his foot down and take it up with HR - a little over 2 weeks later he was offered a new contract giving him parity with his colleagues. That young lad was me and I learned a valuable lesson - know your rights, and never accept anything at face value without at least making sure you have done your due diligence.