From memory you have to have a bound hard copy. If for nothing else where do you put the little stickers?
One could construe that as printing another page of your logbook on PC and attaching it via staples or something.
In addition to my normal logbook, I run one on an excel program I made which adds up just about everything. breakdowns by type, rego, landings etc. Once the data is there all you have to do it type a formula.
Took about 15 seconds the other day to work out the average sector length per year.
But the main reason is that the electronic one is a backup. Every 6 months I send a copy on disk to mum and dads for safekeeping. As you may be aware, if you lose your logbook, then you are credited with the minimum number of hours for your licence category, plus whatever records you can find from the companies you have worked for. No easy feat when you have worked for several who have shut up shop in several states!