A consideration of why nonexclusive electronic rights time limitations matter is for subsequent limited exclusive electronic and print rights, for reprints that want a season of exclusive access, especially to highlight a writer's body of work in a collection, which is best some previously published and acknowledged content and new content not priorly published. Persistent electronic rights time limitations are otherwise pointless and are counterproductive for marketing purposes.
Writer So-and-so publishes several stories off Broadway, and several more on Broadway, and a collection comes to mind, or an anthology wants several for sequential publications. So-and-so's career is ascendant and a novel is in the pipeline. So-and-so's web site links to previous publication, the anthology publisher accesses the works there, and so does the novel publisher considering acquisition, plus, secondary and tertiary discourse, reviewer and lifestyle, publications. Not to mention, readers who are eager to sample So-and-so's previous work in anticipation of a pending new release and afterward.
What? The links are broken, even on So-and-so's web site, because of a nonexclusive electronic rights time limitation, or worse, online publishers phase out backlist matter. How's a publisher and consumer prospector going to conveniently sample So-and-so's work? Instead of insistence upon a time limitation ceiling, for marketing purposes, insist upon a time limitation floor, or insist upon both: Not less than and not more than, say, one year and five years, respectively. Or three years and ten years. Also, insist upon notice of other works included in prefatory content. And for geekus crow's sake, keep the everloving links current.
Back in the day, about pre-World Wide Web, actually, collection, anthology, and novel front matter included reference to other works and where they were available. The era of publishers' default writer promotion and product access through these methods has declined appreciably since then. Novels still include reference to books published by a writer, though only books published by the publisher. Back issue magazine access has declined most. Insist upon acknowledgment of all pertinent works, regardless of publisher and form.
Anyway, negotiate favorable though harmless terms regardless, and terms that promote, advertise, publicize, and package a writer's works and the writer: the four corners of effective marketing. Not to mention, the work res ipsa loquitor -- speaks for itself. The works' merits market, or not, themselves, the productive marketing feature of substance. Access is one side of the phenomenon; merit appeals is the other side.