Lithograving
The hoops are there for a number of reasons. The materials are in storage and time is required to transport to the viewing site. More important though, is that some philatelic archived materials are very valuable like this sheet:

Precautions are essential.
As mentioned some items have been digitized.
For example, several essays of the 1959 Battle of Abraham stamp can be seen on the Canadian Postal Archives site:
http://data4.collectionscanada.ca/n...=POST&p=1&u=http://www.collectionscanada.ca/archivianet/020117/
020117030113_e.html&r=1&f=G&SECT3=POST
Click on "Documents related to this stamp". There are 57 Records.
I think the archives could do a better job digitizing its philatelic holdings. This is something philatelic organizations such as BNAPS or the Royal could get involved with.
A few years ago, a collector donated his county collection to our local museum. Unfortunately several pieces have been stolen. This is the danger in allowing access to holdings. If people are allowed to look there should be adequate security measures in place to prevent thefts.