I don't agree with him but I get what he means, Dante mechanically is the same as 4, just with new weapons. Nero obviously has had more about his combat changed and that excites people. I mean it's simply the difference between knowing pretty much what Dante will play like and not knowing the possibilities with Nero. And not being able to switch arms doesn't instantly kill Nero's combat. Fun Is subjective. Maybe he doesn't need as many options as he does with Dante to have fun.
Nero really didn't had much about the combat changed they just gave him more stuff and made tweaks to his base combat (a more defined and streamlined revving system and they made his gun pretty different). His base combat is basically just an improved version of DMC4 and Nero players will most likely end going harmless pretty often.
Which is the biggest problem with Nero's combat that all his new **** is literally gated and restricted via his breaking mechanic so most Nero players will probably be playing the game more than 50% of the time doing the stuff they've been doing since DMC4.
I honestly see that Nero can be more fun for a lot of people immediately but will probably get stale quicker than Dante and V (maybe). Also don't really knock down Dante's changes and additions to Dante in comparison to Nero's.
-Royal Guard has been altered and functions differently than before to be more casual friendly but at the same time more demanding yet rewarding
-Balrog while having a few moves from previous gauntlets and greaves is basically an unique weapon with how it operate and functions as well as base combos and many more (how it charges its attacks is very different and along with its stance switching system makes it a more unique weapon than Cavaliere).
-Cavaliere and other weapons to be shown down the line
-Inertia is more built into Dante's moveset so moves like Flying Rainstorm is easier to pull off
-Can now cancel ShotGun Stinger into a new sliding shotgun action
-You can choose to equip as much weapons as you want (in any order) and that changes the meta for Dante tremendously
Dante with just 2 new weapons shown off almost as much as new stuff with Nero and his 8 Devil Breakers.
But that is all for now we have to wait and see for more info. Nero is bound to get some more stuff likewise for Dante.