In my experience, it's the players that decide how the game is played, not the system. When discussing the various editions of D&D, at least.
I have found no difference between how my group approaches 4E to how they approach 3E. Other than some of the words used to describe things, the game plays the same. Conversely, I have played AD&D is many different ways in various campaigns (combat-heavy, pure exploration/investigation, political intrigue), so saying that the system determines how the game is played seems incorrect to me.
I believe this is spot on. And, I think, this is what leads to some people thinking their favored system(s) are in fact examples of better game design. Many times, the fix can be as simple as finding a new group (I say simple, but for some that is easier said than done!). As a for instance, the 4e group I was in never grasped the game. Combats were extremely long and tedious and for us, dangerous in the extreme. I don't necessarily blame the system for all of that, as a little DM fiat could have gone a long way to let us enjoy the game more.
Speaking of DM fiat, having the same DM across editions isn't necessarily the answer either. A DM can grasp one system better than another. A DM can be more familiar with a system and therefore more able to adjudicate on the fly to give his or her players the game they want. And, hopefully, this is where 5e comes through on its promise. A streamlined core can be a boon to many DMs and players. Modules adding new layers of complexity can be added when groups are ready so as not to over-complicate things. It also allows groups to pick and choose what lends verisimilitude to their game.
Some folks find lots of rules and dice rolling to add realism. Having rules for contracting venereal disease in a romantic dalliance might add verisimilitude for some. Rolling to-hit, then rolling on a generalized location chart, and further on a specific injury chart to other people is realism. For others still, all of that rolling can get in the way of their realistic narrative and descriptive storytelling. None are wrong about what realism is, because realism is a relative term in the demesne of roleplaying games.
In that sense, perhaps the most convincing reason for those happily playing 4e to try 5e is to see if it works for them and might improve their game. Or, if it is at least as enjoyable, perhaps making the switch is ultimately worth it for updated campaign material or extending a converted campaign? In the end, nothing we say will convince anyone to switch. The onus is on WotC to deliver a game that appeals to whomever they intend to be their market. Hopefully, that is all of us, though being a pragmatist, I realize nothing can please everyone. Well, except for bacon. Everyone loves bacon.
