Cloning, of course, means that a gameplay innovator profits far less than he or she might otherwise by launching an original game; and thus diminution of the value of innovation reinforces all game markets' tendency to become repetitive and boring over time.
The prevalence of cloning in social and casual games is particularly interesting, because cloning was also problem in the 19th century tabletop game market -- but is not a particular problem in the conventional videogame market, the mass-market tabletop market today, the hobby games market, or the mobile games market.
What's the reason for this difference?
It is, ultimately, a consequence of the nature of marketing in the different industries. In the casual game market, publishers and developers spend virtually nothing on marketing and promotion, and simply rely on the firehose of traffic that the portals supply. Similarly, in the social game market, very little is spent on marketing and promotion, with developers relying on the virality of social network user communications to attract players. And also similarly, in the 19th century, advertising and promotion was in its infancy, and publishers relied mostly on establishing as many points of sale as possible and hoping that word of mouth would generate sales.
By contrast, the conventional videogame market spends hugely on marketing and promotion; the mss market game market depends on "old faithful" brands and also spends in the millions promoting newly launched games; mobile games also depends on "old faithful" brands like Tetris, and on games that piggyback on the marketing spend for properties licensed from other media; and the hobby games market depends partly on franchises (the tendency of RPG and TCG players to purchase more product for games they like) and partly on author recognition (boardgamers follow designers whose work they like).
In other words, in markets where cloning does not happen, or rarely happens, it is because an innovator can, through marketing, promotion, and establishing a brand synonymous with a style of gameplay, gain a major first-mover advantage. In markets where cloning does happen, marketing and promotion, and the consequence ability to build brand identity, is weak.
Of course, this "weakness" is also in a sense an advantage; in these markets, game providers' profitability is unquestionably enhanced by the fact that they do not have to spend substantially on marketing and promotion. But the downside is that it is hard to establish brand value, which weakens game providers in negotiations with other members of the value chain, and also makes it harder for them to erect barriers to competition and build sustainable and protectible businesses.
Thus, the reliance of the casual downloadable market on portal distribution has proven to be something of a Faustian bargain; it allowed the market to grow rapidly, but it left the portals in effective control of the market, which they used to squeeze the publishers' and developers' margins, and left publishers and developers with little in the way of a sustainable competitive advantage.
Will social games go the same way? I'll post on that another day.