Like Headless said, the CMC as is don't really need their own spinoff show. They work as a good break between Mane cast episodes and help give a different perspective of life in ponyville while still being main characters, so we pretty much already have that spin-off idea already working and the only reason to go further and completely separate the two would be to introduce new characters or attempt a Next Generation thing. I'd probably watch it, but to be honest I don't think its necessary at all given that there is already so much potential with the setup we have now.
I also don't get why everyone keeps differentiating "being a kid" and "finding your cutie mark". First off, the desire to find your talent and niche is completely reasonable and it is perfectly "kid like" to see kids worry about their future and obsess over what they want/will be, so trying to separate them as if they are different things is just silly. Its a very important topic/lesson to cover for life in general, as you'll see plenty of older people not knowing what to do with their lives, so seeing this concept stretch to cover many areas, in my eyes, is pretty much perfect for a show like this to tackle. Secondly, I thought that the use of "CMC try to find their cutie marks" in season 1 was very well done in that the same overall goal tied into many different lessons and situations so that each episode was never really the same. The cutie marks were only the starting ground for what would ultimately be something more each time and I thought it was very creative to see where each plot thread ended up. Cutie Mark Chronicles was especially wonderful in this regard as it tied the CMC's search into a friendship lesson about connections for the entire Mane 6. Stare Master was also neat in that the CMC's search wasn't the focal point of the episode, but that drive is what lead to them doing all sorts of fun things together like rebuilding the table, playing creature catcher, going into the forest, and all around having fun like they were just hanging out like normal friends would. All in all I think its silly for people to say that searching for Cutie Marks is so terrible when its had so many interesting uses and has had lots of potential while still letting the CMC act like normal kids (which is one of the CMC's finer strengths in terms of their writing like many others have said).
Also, every single goddamn one of you who dislike Show Stoppers are wrong

; Show Stoppers was hilarious and the CMC theme, an obvious parody of 80's glam rock (this show knows how to hit all my personal buttons

), was fantastic and I loved every second of it on my first viewing and I still love every second of it now.
Pocket wrote:My problem with them from the beginning was that, after being introduced specifically as a way to deliver the message that they should be in no hurry to get their cutie marks, their very next appearance has them all eager to get their marks as soon as possible, and even adopting Apple Bloom's tactics of trying everything they can think of. I know this show has some continuity issues here and there due to writers not paying attention, but it's hard to imagine how something that big slipped by them, seeing how the episodes' messages are decided in the writers' meetings before the scripts ever get written.
The end of Call of the Cutie wasn't so much, "Patience is key", rather it was figuring out that not knowing what you will be doesn't make you any less worthy as a person (pony?) as a counter to Diamond Tiara's/Silver Spoon's mocking, and that she was still special and could make friends without a cutie mark.
Twilight Sparkle: Dearest Princess Celestia,
I am happy to report that one of your youngest subjects has learned a valuable lesson about friendship. Sometimes, the thing you think will cause you to lose friends and feel left out...
Princess Celestia: ...can actually be the thing that helps you make your closest friends and realize how special you are. Hmm...
Not to mention that one of the first interactions the CMC have when they decide to get together is literally, "Let's work together for our Cutie marks!", making the Cutie Mark Crusaders (as if their names were any more clear of an indicator) have always been under that foundation of trying to find your talent in life since the beginning of their friendship and they never regressed, nor did the writers fumble on future plots with them.
Apple Bloom: Well, now that we're friends, what if the three of us work together to find out who we are and what we're supposed to be?
Sweetie Belle: Ooh! Ooh! We could form our own secret society.