they shouldn't be that big!
From the developer perspective. I agree. Also they ideally should not be made with HTML5 but with Java.
But from the customer's perspective... If someone finds a nice looking small casual game with nice video etc. Will the size of the game discourage him from downloading the game in your opinion? In my opinion - not at all. Requesting Calls data or Location permission (as it is with Cocoon.IO) will discourage some of them for sure (but that's another topic), but not the size of the APK.
I would say even opposite. People who are not developers and they have totally no idea of the technical things, usually think "wow! this is serious! somethig nice is inside!" when they see game has pretty big size. Because they simply think "the bigger - the better".
Just to be clear. I'm not agains CocoonIO. I've tried it and I like it. Ludei does the great job. Permissions are serious problem but except that, all the rest is ok.
So again as a developer I agree. It is wierd that the wrapper takes usually more than the game itself. But from the other hand it gives you stability cause you are sure that all your customers run the game in the same browser.
But developer's point of view is not really important here. Customer's point of view is the most important.