Just to be clear here...we are talking about the c3-Colle here, right? Not the b3-Colle. [The Colle-Koltanowski versus the Colle-Zukertort]
I would say that "system" openings can teach people plenty if they are approached in the right way.
For example, it teaches the idea that chess study can be made easier by understanding that certain positions call for different ideas. Of course, the student must understand that the system he or she is using may only present a few of these themes for constant use and that eventually there is a need to investigate others, but as a general goal the idea of breaking chess strategy into types of positions with attendant themes and plans certainly has SOMETHING to recommend it.
Secondly, most systems allow White smooth development at the cost of initiative. A Colle player will understand WHY e4 is needed, for example. Understanding the importance of piece play and development is itself a pretty useful idea for early players.
On a related note, most systems emphasize particular piece play over pawn play. The idea of "not putting your piece on an awkward square" has been identified by Aagaard as an under-appreciated maxim for strong play.
Do I expect most beginners to see and gain these things from using a plug-n-play opening? No. But as part of a growing/development program they certainly have
some merit.
And a player can then graduate to some other thematic opening that requires deeper understanding to play well while still being relatively easy to understand in principle. For example, the Benko Gambit or Colle-Zukertort
Grocking why the Benko is so resilient involves a fair amount of good, quality understanding of middle-game and (moreso) end-game play.
There is lots to learn from Gambit openings as well...it's just a different kettle of fish. So maybe you should suggest a newer player to go with the Colle on White and, say, the Smith-Morra on Black.
Hmm..did I actually just suggest someone actually play the Smith-Morra?