I mean, it's kind of obvious why the writers went in the direction of giving the CMC all the same mark. They wanted to give the CMC their marks while still having them be the CMC. That's the kind of planning that implies that we're going to get future stories from them. So clearly we're going to get future episodes where the CMC does their thing going around helping ponies get their marks or understand their marks or whatever. They'll probably get some official royal stamp of approval from Celestia to be the royal cutie mark counselors since every major character in this show is the most important pony ever.
Yea, i actually think that it would make more sense if there were more established guidance counselors in Equestria if DT is anything to go by. In a world where you effectively wear your heart on your sleeve (rump) as a definition of who you are for all to see, it must be pretty devastating to not know what you are 'supposed' to be doing with your talents. And with not only DT, but characters like Troubleshoes, it doesn't seem to be all that rare of an occurrence.
So I am fine with the CMC doing what they are likely gonna be doing and being Cutie Mark Counselors instead of Crusaders, personal issues with the actual mark design aside.