Why bridge...Do bridge players collect like poker deck collectors? I have never heard that.
Not really. There are collectors, but they specialize in the custom backs more than the fronts, like the artwork you see on the backs of bridge sets.
Bridge cards are popular for play in parts of Asia, China in particular, according to Lee Asher - smaller bodies, smaller hands. Most of the world reserves them only for games requiring a lot of cards in a hand or (in casinos and professional gaming rooms) for Texas Hold 'Em poker (easier to conceal your hand when peeking).
This is just a great example of someone with more enthusiasm than practical design.