I feel like I've had the opposite experience in the gui (maybe a KDE issue?) closing gui windows frequently lock up, and I find I frequently have to drop to the command line in order to properly kill some programs
That's because the end proces of the GUI sends a sigint, which does jack shit if the program hangs, you only archieve for a higher parent process to obtain it until it can off itself gracefully. You need to right click the process and send a sigkill signal to emulate the command line.