Let me say, for someone who knows wget, this is not a horrible interface.
A tabbed interface sucks here because I have to click through each tab anyway to see how the defaults are set, or I have to internalize the defaults for the gui - more work for me.
There’s no need to search for anything here - all the options are right up front, no more ‘press F1 for help, search the index, come up empty and have to click all the damn tabs anyway’.
I might move some of these controls around a bit, to make them easier to target, but I like them all on one page like this. All I want the GUI for is so I don’t have to read the man pages. Again, that’s assuming I know what these options are for.
Now, if I didn’t know wget, or this app was supposed to be “wget for dummies” then yeah, sure, make a wizard, or tabs, or whatever so a n00b can learn it.
But put a user of this ugly gui would have a much easier time moving back and forth between gui and cli versions of wget than a user of a pretty, dumbed-down, colorful version would.