I agree with the harder steps/use challenge for every song.
I also would much rather play offical hard steps than some random keyboard smash that some one was like "Lolz, no one will ever beat this!!!!"
Don't get me wrong though, I do love the true dance songs that make it in with a smooth 7 difficulty that is just a blast to play. Makes me feel like I'm really dancing, even though I'm sure I still look like a complete idiot. :P
I think better player intergration is the key here. They finally did it in Japan, and just barely did it too, with SN2. e-amuse allows for player data to be saved, thus allowing stats and achievements(look at the XBOX360, it's like crack... :P) to be tracked. THEN, unlockable challenge steps for classic songs. Seriously, this is a freaking awesome touch that I wish there was just so much more of. I know e-amuse has been around for a while, and in other Bemani it means way more than tracking scores. You get to unlock songs, charts and other items, totally cool.
SN had e-amuse but just to track scores, it's neat to see that it's a step up in SN2. I still think they could do more though.
Imagine having more unlockable challenge steps for every song. Like AA the heavy chart, unlock the challenge chart for that song. AA every song in a series(any difficulty for all players)(DDR Max, DDR 4th Mix etc.), unlock a special awesome remixed song from that mix. The remixed songs in DDRMAX2 were awesome. And I thought it was even cooler that they were ONLY accessable in Oni mode. Made me feel hardcore when I was playing them, when others couldn't even reach those songs. Then having all of these stats tracked online and accessable to the players gives that intergration I was talking about. Making the player more involved.
I do think Marvelous intergration to normal mode will improve the challenge here too. Now maximum scores are no longer a dime a dozen for every player. Puts it on the level of IIDX where very, very few people have the max score on very few songs.
And on a final note, Extra Stages are the bomb diggity. :P They just feel like that secret boss in a game. And I mean "true" extra stages, not the select a song extra stages. I think extra stage should always be locked. I'm just a jerk though. :P
For the TL:DR crowd, my points are bolded. Thank you for reading.