Representative Weiner sent numerous photographs of himself to complete strangers. Some of them were suggestive. Others were explicit. Is that enough that he should resign from office? After all, President Clinton took phone calls while being serviced by an intern. Is Weiner worse than that?
Yes. Weiner is an exhibitionist. He exposes himself to strangers. If he was doing in person what he has been doing electronically he would be arrested and charged with a misdemeanor. In some states he would end up on a sex offender list. In contrast, Clinton had an affair. That is disgraceful but not illegal. Side note - Clinton was not impeached for having an affair. He was impeached for lying under oath.
But that is not the real reason that Weiner should go. He should resign for the good of his party. Following a win in a special election, the Democrats were planning a full assault on the Republicans over Medicare. They already have ads made talking about how the Republicans want to destroy Medicare. It doesn't matter that the various fact-checking organizations have ruled these ads outrageous.
But none of that has happened because no one is paying any attention to the Democrats when they talk about issues. All the press wants to talk about is Weiner. If Weiner resigned then the stories would stop. In the meantime, the Democrats cannot get a word in edgewise.