there ARE websites where you can find war3 resources.
they're just a goodle search away...
starting up worldedit is really not a difficult thing.
and in the end all u need to say is "i want it to look like that 2 headed dragon thing but with this funky colors"
so i really dont get where the issue is..
I guess there is no issue, but if one was new to wc3/fs and about to put money in to get a custom unit and he finds a textbox asking for skin/model name without any more clarification, he might become hesitant. Maybe something to indicate that you can also explain the unit look or that you will be contacted later if it wasn't clear enough. That he knows FS-staff wants him to get what he wants! 
One might:
1) do a search or find the model name from the editor (GOOD) or
2) ask from another person, to find solution (GOOD) or
3) Hesitate and forget about it and continue without, because he wasn't sure (BAD).
For example I had to check if Wisp had different modelname(s) and soundset(s) than just "wisp" from the editor, because I didn't dare to put wrong names there.
Another example, I got asked by another player about a unit name, that if the specific name was correct and supposed to put into that textbox. I guess some people just want to be carefull.
For advanced enough user nothing might be hard and vice versa, but they might still have money to spend in fs 
