Honestly, Mario needs more innovative and experimental game play these days. The only time he needs stories are in rpgs, but they need to be done well. Look at Mario and Luigi 1&3, lovely stories, and even somewhat more mature (I mean he was fighting terrorists, who sought control of countries rather than "OH LOOKIE I GOT A PRINCESZ" "FOR NO REAL REASON EITHER, THAN CREATING AN OBJECTIVE". While Mario and Luigi 2, had an interesting concept with time travel, the actual storyline was just plain dumb and rather uninteresting as a whole. I was severely disappointed with M&L2.
Each game did have new and interesting characters, while in the second I just felt they weren't really implemented well.
Also as far as Skyward Sword goes, yes it does have new main adversaries, but they truly aren't anything special and I honestly wish they would have done something much more creative with Ghirahim's fights. They were literally the same fight, just pumped up a bit in difficulty each time (the first part of his final fight does not count as a fight, it counts as a time filler). While the final boss is seemingly out of nowhere in regards to his design and doesn't really fit into game because of it. Not to mention this is very poor build up in terms of his fight, which was so easy the first Ghirahim fight actually seemed more like a final boss because you had to actually follow the movement of his hands( I actually had to fight him 5 to 6 times, before I actually got anywhere, where as the final boss (Demise) only took two tries to figure out his rather bland attack pattern even in the second half of the fight, and then defeat him).
Each game did have new and interesting characters, while in the second I just felt they weren't really implemented well.
Also as far as Skyward Sword goes, yes it does have new main adversaries, but they truly aren't anything special and I honestly wish they would have done something much more creative with Ghirahim's fights. They were literally the same fight, just pumped up a bit in difficulty each time (the first part of his final fight does not count as a fight, it counts as a time filler). While the final boss is seemingly out of nowhere in regards to his design and doesn't really fit into game because of it. Not to mention this is very poor build up in terms of his fight, which was so easy the first Ghirahim fight actually seemed more like a final boss because you had to actually follow the movement of his hands( I actually had to fight him 5 to 6 times, before I actually got anywhere, where as the final boss (Demise) only took two tries to figure out his rather bland attack pattern even in the second half of the fight, and then defeat him).