2. Lesson the power of the Nexus to have it do time travel, endless life, 3-dimensional travel, fulfill your geatest fantasy, compel you to come back. Its too much, too incredible. Use good writing to get over script problems, don't apply more magic.
I always thought they should have "stolen" an idea from Forbidden Planet; have Veridian 3 be the site of an ancient and powerful machine that can make the users greatest fantasy become reality, essentially a reality warping device of sorts. It needs an exotic energy source, such as the Nexus ribbon to power it, which the original inhabitants did use but the disaster which ended their civilisation knocked it out of reach of the planet.
Hence Soran needing to change its course back with the destruction of various stars. In addition to him getting his family back, Soran would tempt Picard with the prospect of creating a world in which the Borg ceased to exist, in which Picard had never been assimilated and used to destroy 39 Federation starships and the loss of around 11,000 lives. At the end of the film Picard would alter the control mechanism so as to use the ribbon to completely destroy the device. A decision that would have repercussions leading into the next film.