Hansard is a record that has to be available for hundreds, if not thousands, of years. Given the fast-paced world of technology, there is a risk that the format of the content would be such that, in a relatively short space of time, the digital version is left unreadable by whatever the latest gizmo is at that time, or that there may be an ongoing requirement for file conversion as technology moves on, also at a cost. MPs need little excuse to forget their past as it is; "saving on file conversion costs" is a luxury we should not afford them as a further means of escape from error or wrongdoing. Printed-and-bound should be mandatory; e-versions are relatively simple and cheap to derive from the source of the printed one.
Writing it is what costs the money, this wouldn't save anything, and if it's anything like other government IT projects would end up costing a lot more, and probably would work so poorly that it would have knock-on costs of wasted time.
Democracy isn't free and I don't think this is the sort of thing we should be scrimping on.