That was changed at the request of developers who complained that some were spamming the release list with minor updates just to keep an app on the "latest releases" list.
I think you need to reexamine your cost-benefit analysis. Under the current system, yes, a new feature will not generate new sales at the same rate because you don't get kicked to the top of the release chart again. On the other hand, adding features and fixing bugs helps maintain a positive relationship with your existing clients, who presumably count first in your potential audience for future unrelated releases.
Many of the comments associated with low user ratings in the store relate to non-responsive developers who don't reply to support requests and don't update their apps.
So it cuts both ways.
Yeah, I know where you're coming from, but seriously this will affect the quality of my work in future. I know a guy who also writes iphone apps, but puts out some real crap - he gets bad ratings, yes, but doesn't really care because he's still making good money. I do actually know a guy like this, he's a friend of a friend. I'll show you how our methods compare, up to now:
Me: I spend the time writing a decent app. It gets good initial sales, then if I'm lucky it gets into the charts and continues to sell at an OK level. If not, it sinks from the charts and my income disappears.
Updates - if it's out of the chart, an update would give me another income boost, paying for the time. If it's in the chart, the income boost is minor, but it helps me to stay ahead of the competition (or catch up if they go past me..)
Other guy: He spends as little time as possible, makes something that sounds good or useful, and gets a decent spike of initial sales. Then people realise it's rubbish and get angry, but he's already well into the next one.
Updates: A quick spelling fix or minor change took a few minutes and sold more apps.
After the recent change, the other guy will just continue writing crap, and getting paid for it. He won't bother with updates, but he'll probably make 2x more apps instead.
For me, if I update now it'll keep my existing customers happy (no income here), which will improve my rating. That will help keep my app in the charts a little longer, but if my app is decent in the first place it'll make very little difference. The extra income will be small. It won't help me to stay ahead of competitors or catch up any more too, because you need an additional sales boost to do that, and that no longer happens. If my app is out of the charts, it'll make zero difference.
Just to emphasise that, I just updated one of my apps that was out of the charts. Normally, that would earn me a reasonable amount of money and put me back in the chart for a while. This time, i had zero additional sales. Not one. Sales were actually down on last week. Will I update that again? No.
See what I mean? I won't bother updating in future, as much as it pains me to do it (I do actually care about my customers - that last update had 2 new features requested by cusomters!) there's no incentive. If I spend the time on a new app I'll make some actual money instead.