All portals, including BigFish and the Apple AppStore, want to own the relationship with the customer. You, the developer, are an interchangable cog in that plan -- you can always be replaced. The customer comes to their storefront, their name shows up on the bill, the customer thinks they are doing business with them.
This is about as conducive to building your own brand loyalty as it would be if I grew up listening to Californication by Best Buy. Want to develop a mailing list, a following, upsell users into other products of yours that they'll find interesting? Well, that is going to be a little hard because the portal wants to do all these things and they'll actively prevent you from doing them.
To add insult to injury, you have to pay the portal 60% of your sale price. (The portal will phrase this, of course, as "We're generously going to allow you 40% of our sale price." Always remember, it is THEIR customer.)
Now, why would anybody put up with this? Well, to be blunt, most programmers suck at marketing and think they can't do it themselves. The portals do not suck at marketing and have distribution nailed. Thus developers get in bed with the portals and, well, its all over but for the crying.
You are much, much better off if you sell software on your own website, assuming you can get people to actually visit it. This is another reason why I warn people off of games: the ways I know which are really viable for small software publishers (SEO and CPC advertising) really really suck for games. People don't search for software, they search for problems and solutions to problems, and nobody has a hole in their life that they know only a dragon-themed match-three game can fill.
Oh, the natural dynamics of games (constantly increasing asset quality expectations) plus the incentive of portals to drive volume by maximizing selection through stomach-turning churn rates means that the sales vs. time curve for them looks like walking off a freaking cliff. This is unfortunate, because you can't do the "fire, adjust aim, fire again" learning process that categorizes most successful small software development. And, since you're not building a brand or a list, you aren't really developing any assets which can be used to make the next product more successful or less of a crapshoot.
On pricing: far too many people who play games have expectations for truly staggering development budgets to justify minor expenditures, and that is ignoring the large contingent who will steal the software given half the chance. Getting $2.50 on a product which took $100k of implied labor (a man-year for a single senior developer, not really that hard to imagine for a game) is just painful to think about.
Back in the real world, because you're addressing problem-sized holes in people's lives, you can charge more. A LOT more. I think at least a thousand people have bought Bingo Card Creator for $30. I get to keep about $28.85 of that, less expenses. The math gets more attractive than $2.50 a unit in a hurry. (Not to mention that $30 is, ahem, fairly cheap. You should see developer tools or B2B.)
Meanwhile, I get to keep a bit of a springboard towards future products and, of course, improvements.