As i see it Zeppelin had awesome quality control that lead to a pretty much perfect run of lp's
You have so much left over material from other bands because of certain factors
1 Other bands spent lots of time noodling about and discarding things which leads to leftovers
2 Zeppelin had a clear idea of what they were going to achieve before they entered the studio
and got in and out as quickly as possible.
3 Everything was used up by presence
4 Most bands have a creative span of 5-6 years
Taking this into account Page wanted to refresh the catalogue wanted to add value
felt this portal idea was the way to go and didn't realise the hardcore fans wouldn't see it his way.
Personally, while expensive i think the superdeluxe boxes are beautifully realised works of art
the extra content is just that, extra, take it or leave it!