I didn't see much difference on the attempts done by Ace3 and IGAS to wrap behaviors of UI elements (AceGUI, IGAS.Widget), handling events (AceEvent, IGAS build-in event handler), providing timer service (AceTimer, IGAS.Widget.Timer), abstracting addon and module structure (AceAddon, IGAS.Addon), providing namespace (LibStub, IGAS namespace system), etc.
They are trying to do the same nature thing. Obviously these features are demanded by many addons - many authors built them by themselves, many authors turned to Ace3 since it's the most popular one - because they've got experience from other high level language.
However, the approach of IGAS is different from what Ace3 does. It has a more intrusive structure, to provide a different access chain. That's why you don't like it at the first time. Lua is a light-weight language, and you got used to its simplicity and rules.