I’m seeing a lot of people saying Morgan/Garcia wouldn’t happen because of the way she looks, or that Morgan/Garcia would have happened if she was skinnier. And I realise my opinion is not the be all and end all here. And I’m not trying to do that guy thing of being like ‘well I find her…
I agree that they’ve never written Garcia as unattractive or addressed her weight in any way. But as far as relationship goes… I think both Penelope’s and Derek’s love interests could’ve been less stereotypical - because that’s what make people relate Penelope’s weight with her not ever hooking up with Derek. Morgan’s always Barbie-like girlfriends responds to the kind of women that would conventionally “match” him - like cheerleaders match the popular hunk in high school.
The same goes for Garcia and Kevin. Could it have been any more conventional? Just adorable enough for a five-season long storyline with a character that looked like a male carbon copy of babygirl. Sam is slightly better as a character but is still more to the nerd side than else. Both again respond to the kind of men Penelope is expected to be with.
So when people watch that onscreen, they understand that Penelope is good enough only while the flirt doesn’t get real - for they only get real with their ideal “types”. Even if it is not their intention (and mind me, I too do not believe it is), that is a message that inwardly comes across.
I tend to agree more with your idea that they don’t get them together because of narrative issues. But I think an “easier” way to make everyone happy is have them together at the very end of the show. That way they’d turn around the meaning of all these typical love interests to imply that your “match” is not always visible or obvious. Also an endgame would save them from further developments and narrative changes. It’s what I’d do as a writer.
Then again I’m not on Criminal Minds. Aw shucks! :)