[ Dogs ] Open Question : Why is 'clicker' training recommended so much?

I have a 13 year old lurcher and a 15 week old border collie. My lurcher went to obedience classes when he was a puppy and I also taught him tricks (speak, kiss, paw etc) and all this was done without a clicker. I have also taught my 15 week old puppy to speak, sit, down, paw, all without the 'clicker' and just using treats as a reward. Why is the 'clicker' raved about so much? I dont want to rely on a 'clicker' to train my dog incase he only does what he is told, if he gets a 'click' at the end of it, which is then usually followed by a treat. When I go out with him, I always have a pocket full of treats so when he comes back when called, he sits at my feet for a treat. I cannot understand why 'clicking' then rewarding is so important to teach a dog anything?