0plus1, I agree AppMobi working would definitely make a significant difference in the sales on construct2, However I personally do not think it would be fair to charge for a additional license on top of the standard or business license.
If you really want a engine like Construct2 that can develop for IOS Take a look at http://www.stencyl.com/, There is a free version which is amazing, The free version has no limitations or missing features. But you have the option to buy the IOS edition for ?99 I think it was, Which is a completely different engine, The free version is a flash based engine, The IOS version is HTML5.