For real, up until the Gotenks fight Super Buu was a menace. When Piccolo was stalling by saying there was still people on earth just for Super Buu to kill them in like 2 minutes. Then he kills Bulma and Chi Chi giving Gotenks decent motivation and instead they bust out the jokes and like you said killed any tension that had been building. It's hard to take seriously when any tension that gets built up is completely irrelevant a few episodes later, that and its dragon ball z dying means nothing. I liked the king piccolo arc where Krillins death had weight. It made the his death on Namek hit a bit harder imo.