In the struggle to incorporate new, and even next-gen features into a fighter, the developers are at great risk of creating a product that is neither here nor there. In other words, the final product can be something that doesn't work as well as last-gen conventions and falls short of the aims and goals of the next-gen design elements. What's even more dangerous is last-gen design elements often have a caustic, poisoning effect on the next-gen design elements when mixed together in the same game.
It is unfortunate that the creator of the Super Smash Brothers series failed to embrace the community of players that gathered around his games. Because Masahiro Sakurai created Super Smash Brothers Brawl completely on his own, often making decision out of negative reactions to the smash community, Brawl greatly suffers from mixed-generational design: when a game contains design elements from at least two different generations of design conventions/approaches that naturally conflict with each other.
The core next-gen design of Super Smash Brothers is essentially "everything is dynamic." Because the core of Smash centers around attack moves, we'll look at attacks and their effects to deliniate the mixed-generational design in Brawl.
Keeping the core of the game depedent on factors that both players control keeps the attack results varried enough to prevent universal combos or confining strategies from developing. The effectiveness of attacks is initially the result of two sets of factors.
1) How much damage the target has.
2) How much the attacker has weakened the attacking move.
Then there are a few more factors that come into play.
3) The targets can influence the trajectory of their flight by using DI.
4) The environment can create opportunities for the target to stop itself, rebound, for the attacker to pursue, and/or a variety of other outcomes.
Beyond these dynamic factors, the core of Smash is designed so that moves naturally decay with repeated use. For example, Mario's cape (side + B) floats him in the air upon initial use. But with each additional use of the cape, Mario floats less and less falling closer and closer to his normal fall speed. This decay property is designed so that players can't stall in the air with Mario while adding a dynamic property to the move. Marth's dancing blade in Melee behaves the same way.
Last-gen fighter design, which is the opposite of Smash's core design, typically doesn't have any dynamics in their hit stun system. No damage based variability. No stale-move negation. No DI. And certainly no level dynamics unless you count the invisible walls that characters sort of float against so that they can be comboed more easily. Such design at its most extreme can result in infinite combos that start from quick simple hits that, once started, are virtually impossible to stop. Not only does this design constrict competitive strategies to preventing these devastating, and at times game ending combos, but it doesn't leave room for any interplay. In fact, once these combos start, the only thing left for the second player to do is hope that their attacker messes up. In Smash, the dynamics of the level and the ability for the stunned player to DI in order to throw off their attacker's approach keeps things interesting and interactive.
In Smash, any element of the game that isn't as dynamic as the core design or that stems from the last-gen design, works to completely obliterate the next-gen core design of Smash. It's not a matter of preference where some players can prefer to use the last-gen elements and the two types of people simply have to fight out their differences. True leaps in design reflect leaps in perspective.
The way the core of Smash is designed teaches the player to think through problems to find a logical, visual solution. The core of Smash teaches players that when things look bad, there is always a way to influence the situation to your favor. But the glaring last-gen design elements in Smash flies in the face of these teachings. Infinite combos that ignore dynamics and variation. Invisible attacks that betray form fits function.
There are many last-gen element that corrupt the core design of Smash. Here's a list of a few.
It's a shame that these poorly designed characters and elements are dominant in the competitive tournament scene. It doesn't surprise me at all. Essentially, a character like Metaknight ignores the dynamics of the core of Smash in favor of unquestionable priority and unwavering ability. Give players a choice, and they'll probably pick the over powered characters even if they destroy most of the game in the process. These glaring mixed-generational design make Brawl play more like other fighters like the following....
Street Fighter
http://www.youtube.com/watch?v=68tQ3qNQuRU
http://www.youtube.com/watch?v=PDYANa9a-mU
http://www.youtube.com/watch?v=SRK812jaJjI
Guilty Gear XX
http://www.youtube.com/watch?v=TUZb45qYEjY
http://www.youtube.com/watch?v=dLHOEfsWmGM
Marvel vs. Capcom 2
http://www.youtube.com/watch?v=avvrMO9Smao
What a shame.