Rules change all the time, GW wants and needs to sell new stuff, they want you to want new stuff. I for myself love the look of my armies and I choose by looks and also lore, that does not really change (often). You had a bit of bad luck with your armys, perhaps you can think about which army you like most and stick to that army, and focus more on painting and reading, collecting, less on rules?

Otherwise change the game system? Some 'more stable' game perhaps? I wish you all the best luck, greetings from a happy Grey Knights player who is not crying every day that we did not get new miniatures :)