GUI mainly influences usability. Usability will be more important once many people start using CryptoNote coins as currencies.
At this point no CryptoNote economy is well established. Technical differences between coins are more important than GUI concerns at this point.
Boolberry has a GUI but it is not our largest advantage.
https://twitter.com/BBRcurrency/status/627037831412756480Can you tell how long do you have a GUI wallet?
Trolleros devs think that the important is to have a CLI, lol, no upgrade is needed.
Please respect the Monero development team. They have done many interesting things already, such as OpenAlias which is now being integrated into Electrum. My post was clear. I do not think a GUI is the most important thing at this point. As an economy develops it will become more important.
As others have pointed out, web wallets and 3rd party solutions (like Electrum) can also play a role