anyone can learn the shadow clone jutsu,
his clones can
do jutsu
be kage level clones
his clones can even summon more clones
he's taken the shadow clone jutsu to new heights
plus he can create hundred of clones with ease thanks to his chakra reserve
Not to mention Gaara can make sand clones that are, in essence, very similar to shadow clones. Sasuke probably CAN do shadow clones but: 1)he would NEVER use any technique/style that is similar to Naruto's(the whole rivalry thing), 2)he probably already realized that he would never catch up to Naruto's skill level of shadow clone usage(since it is Naruto's primary technique) and 3)it would probably turn off a lot of fans if Sasuke suddenly started spamming shadow clones. Personally, I like the fact that everyone has their own unique style of fighting.
That being said, I wish Shikamaru and Rock Lee had more air time in the manga. Imagine if they evolved to the next level. Imagine this: Sage mode Rock Lee with Chakra gates released and Shikimaru Shadow Cloak(let it simmer for a while). I kind of like the Shadow Cloak idea. Basically, he evolves his shadow techniques to the point where he can envelop his body in Shadow and have the all the strengths of the Shadow Techniques. I would love to see that.
Sorry, just a REALLY random tangent. Anyway, shadow clones are cool, but not everyone should use them.