That thing you're complaining about? Someone worked really hard on it.
Working on any software project can be frustrating. You inevitably encounter things that are confusing, buggy, poorly documented, over-architected, under-architected, and so on. In an open source project, this frustration is compounded when uncertain resources and volunteer contributions lead to inconsistent quality or completeness. Working on the development version of the software adds additional challenges, as you have to learn new systems and development paradigms that may not yet be very refined.
Think twice, though, before publicly venting your frustrations about how awful that current pebble in your shoe is. In a project like Drupal, chances are, someone you're talking to worked really hard on some component of the thing that's frustrating you. They probably donated their time. They did the best they could with the resources they had.
Negativity is contagious. Even if you have good intentions, and the person you're talking to has good intentions, disparaging remarks will quickly take your discussion off track and make both of you less interested in solving the actual problem.
If you disagree with something in Drupal, first, take a deep breath, and remember that the thing frustrating you is the work of real people. Then, take the time to file an issue that neutrally states the change you suggest and the reasons for it. Be constructive. Bonus if you provide a patch to get the issue started. The same feedback that started an argument when you threw in a couple hyperbolic adjectives may be received with enthusiasm if you phrase it professionally.
Be nice. Sometimes it's hard, but it's worth it.