Funnily enough, I'd guess that they were actually trying to avoid
the sense that they were shoehorning things in; those things being Picard and the Enterprise
. As you say, they clearly wanted Picard there to launch the new show and provide some welcome familiarity/reassurance. The Jennifer/Wolf 359 backstory was, I'd hazard a guess, intended to justify Picard's presence in the story beyond that - having established that the good captain would be in the pilot, I assume they wanted to tie him to the new lead in some fashion. Get something out of it other than "here's Picard. So...er, have fun..."
Having Sisko's wife die at Wolf 359 must have seemed a good way to do that, a way that provoked a bit of drama and avoided the pat and obvious connection that Sisko was some old friend of Picard.