It is very easy to understand.
Many of people who like movies, especially not the mainstream ones, consider each movie as a unique being, having its own substance, do it deserves a nice and special treatment
Like all retail dvds or BDs, it deserves to be burned to disk, having a custom or retail cover etc.
I realise that some of them, like your dad, rarely pull out a DVD to watch a movie again.
May be because every day more movies are added to the collection!
Although I can understand his point, which could be same for me.
At least to me, the point is to have every movie in order, to a certain place,
visible (because even seeing a home made dvd case with a movie
can be ..pleasure, like seeing and enjoying a collection of vinyl records

) and then to have the option to pull out any of them and watch it!
About your 3TB hard drive storage, I am sure you will find out that is is very liittle, especially if you like
HD or full dvd movies.
In that case, and since you do not burn dvds to gain hard drive space, you will find out ....really soon
