If we're just wishing for what we want; then let me tell you what I want...
That every person who plays 6E will control their own destiny. An edition of the truly free! An edition of declaring action, not spewing words; ruled by judgement, not committee!
Where the rules change to suit the...
Instead of thinking about rules, I want to think about the training process of the developers.
For example, I think the developers should participate in UFC style matches to better understand how unarmed combat works.
Or go spend a week camping and hiking. Or maybe go forge their own swords???
I want 6E to purposefully push out and purge the weak from D&D so that the strong won't be held back by trying accommodate the weak.
I also want WOTC to consult heavily with the members of Enworld; as who are better then us to determine the direction of D&D??
And instead of a DMG, WOTC could...
Ravnica is all about Guilds, so my central questions are...
Which players will be from which guilds? Will they all be from the same guild or all different??
Which Guilds do you understand and/or can portray?
How well can you manage fractional conflict? One group like something but another...
But exploration and social stuff shouldn't require rule systems! The DM and players are suppose to improv and negotiate their way through it! And having class abilities for it will just encourage people to look at their character sheets to solve problems. They're suppose to use their...
Your character can fight a tank but can they track down Carmen Sandeigo? And yes, I literally did throw a "where in the world is Carmen Sandeigo?" type adventure at my M&M group.
That reminds me, the Invincible TTRPG is having a Kickstarter; eventually...
https://www.kickstarter.com/projects/1192053011/invincible-the-roleplaying-game
Oh, we're looking for common pitfalls, eh?? I find expecting your players to read the rules to be a common mistake among designers. How do you design a TTRPG that doesn't require players to read???