eyevet, I think Canada Post's and the Royal Canadian Mint's sale of collector's sets/items are not quite analogous to the Bank of Canada's production of replacement notes.
Canada Post doesn't care if someone buys up all the 10 cent stamps because they can just print more to sell, as postage is not part of the money supply and doesn't influence the economy.
The Mint produces items expressly for sale to collectors {how else could you get an 8-cent coin?
}. True, circulation coins are part of the money supply, so I expect the economy could get screwed up if people started hoarding certain denominations of coins for some reason.
However the BofC's intent with * and X notes was to replace other notes damaged in production, so I expect the BofC thought it was pointless to continue producing these notes - which were intended to be used in circulation - if most of them were never going to circulate as part of the money supply. Why spend 7-8 cents to produce a note if one person is going to end up taking it and socking it away somewhere?
I guess the BofC could go the route of the RCM and try to cater to collectors - they have made this concession in the past by selling uncut sheets of notes and the "Lasting Impressions" sets. I suppose they could print individual, or sheets of, * or X notes for sale, but then for many people this might kill the fun of seeking/collecting replacement notes, as might an "error note" manufactured and sold by the BofC {but at least then you'd have a genuine error, not like that double-denomination "error note" that sold on eBay with a $5 image ink-jet printed on a $20 bill!}
But I don't see why the BofC cannot, as you suggest, print more varieties of commemorative notes to mark important dates, events or people in Canadian history...the BofC must have known that the majority of 1967 $1 notes would not be spent...what's wrong with commemorating a provincial anniversary? I don't know about a note to honour Pierre Berton, though - certain groups may boycott the note and refuse to accept it. This gentleman showed us all how to roll a joint, remember...so he is a bad role model for today's youth, he offends the religious sensibilities of many Canadians, he promotes a hedonistic and illegal pastime, yadda yadda yadda...