Yeah - the entire point of collectibles is the attachment to history. Collecting is a fundamentally sentimental human affliction.
No other physical bitcoin could be as tightly coupled with the progress of Bitcoin in general as Casascius coins; from inception as an experiment in 2011, to termination due to concerns regarding regulatory overreach from FinCEN. Plus almost every news article between 2011-2014 using a Casascius coin stock image in their story...
That's the kind of history that collectors will want to own a part of down the road. The newer physical bitcoins may have some temporary novelty, but none will ever match the relationship Casascius coins have to the Bitcoin experiment. Look at the history of other coins and collectibles... In the long-run, the story often matters more than the rarity (to a point), and Casascius coins have both.
Well said ^
I agree completely and it is the reason my collection is solely Casascius coins!
I assume if BTC rises again it might pick up a bit. 
