A GUI is of critical importance for the next level of adoption.
I disagree. What incentive does anyone outside of our community have to run a full node with a GUI? How many Bitcoin users do you think still use QT?
The "next level" of adoption comes from third-party integrations and services that actually bring utility to the currency. A bundled GUI doesn't deliver any compelling new use cases, and won't result in
any new adoption outside of Bitcointalk users and their close relatives.
Well btc has many options such as Armory, Electrum etc while Monero has very little although Trezor is coming.
Also it is my understanding that the Monero GUI is going to be kickass but I don't know how it compares to QT.
Bottom line is that the GUI is a very welcome addition.