What's crazy is the idea that the average joe will want to run a node for some whiz-bang e-money just because he can... never mind the fact that he has no reason to.
A bundled GUI only increases accessibility to the few crypto-conscious individuals already in the space. Joe Blow doesn't have a good reason to run his own node, GUI or not. Making something easier doesn't automatically make anyone want or need it.
There are lots of things that can make XMR approachable to wider adoption. Mobile apps with easy messaging as an abstraction layer for payments, point-of-sale tools and services for in-person purchases, easier exchange services from/to fiat, etc. would all be greatly helpful.
But a core GUI won't increase adoption significantly, because average users won't be running their own nodes anyway.
Sure, I don't run a node for Btc, but that coin is several iterations past efficient CPU mining. But Monero, afaict, will be still CPU mineable, right? THAT's my motive for running a node. As someone else here pointed out, going through the hoops to mine Monero NOW is a "chore". But once the gui is out, if it has one-click smart mining, I'm there! Giving everyone a motive and an easy way to run a node is decentralization in action, as exciting in its way as fungibility and privacy!