Sounds contradictory, right. Well even though I've mentioned points in which grades can be the most important differentiating factor let me tell you why I think its not the most important factor. The answer is success and my definition of success here is excelling in one's particular field in the long run. And to me, the things that matter more would be the quality of the person, his passion, hardwork and directed effort in his field. Decisions at important junctures and luck are also important based on experience. CGPA is too minuscule a thing to capture all those aspects to play as the most important factor in the long run. But again, if you've got relaxed and thinking about caring less about your grades let me warn you if you compromise on grades you should back it up with something else to show that its not just lax attitude or lack of competitiveness that got you there. In my experience, people with better CGPA are more often than not are more hardworking, sincere and likely to succeed in future. Also lower grades often lowers your confidence which may hamper your prospects in the short run. Its one of those things that you rather would like to have than not.
Seen people with 5,6,7 GPA doing better than 8 pointers and definitely seen the other way round. So know that there is no rule. My best advise would be to treat them as school percentages, always better to keep them high to keep parents, peers and society happy. A balanced approach is the best approach at the end of the day.