What do you mean by "just removes the icon". When you uninstall a 3rd party app on iOS, it's gone.
And I don't know about the stock ICS version of the Nexus 7, but on devices from Samsung, LG etc, stock Android has some annoying (e.g Facebook) "stock apps" that cannot be removed, unless you root (and with a jailbreak I can also delete stock Apple apps).
Of course I'm just talking for the technical side of things.
As for freeing up space... unless you are short 20 MBs or 30 MBs (what is that, like 4 songs?), then obviously disk space is never a problem (and if you have a 16 GB device, Android, iOS or whatever and worry about 20 MBs then you needed more capacity to start with).
?????? You just use the app switcher, giggle mode, bang, it's gone (and if it has been on the background for a while it won't use resources, as it's been proven many times via tools like Xcode's Intruments). So I don't understand the whole "kill all applications" part (since you discuss power slider, then you must NOT be referring to a case where the phone is stalled completely).
What rogue apps?

And anyway, part of what you say might be true, but despite the few ugly ones that get past the probation stages, I think it has helped the AppStore to keep a consistent level of quality.
If you look at some of the top apps, you'll see their UI and all is very consistent, something that sadly doesn't happen on Android, where at times I feel like every app is a whole different world.