Who honestly knows? PES 2016 could be better, it could not be. Gameplay is #1, and as you said, it isn't something you can see. As for the trailer, of course it looks good, any trailer does. I personally did not like the feel of PES this year (here come the insults about liking arcady football only haha). For someone that picks apart EA and FIFA 15 as much as you do, there could already be things in this PES trailer that I can see people complaining about.
0:17 : Where does Neymar get that strength from?
0:22 : That passing play can easily be replicated in FIFA 15. Don't lie to yourself if you don't think so...
0:40 : OTTTB OP!....
2:27 : Build up Long-pass...again nothing special here, OTTTB OP.
2:35 : Positioning Flexible play ; I have done many times.
And just in general, if this was a FIFA trailer I could already hear all the BS... people complaining about the phone celebration being stupid, how crawling back up to your feet after getting tackled isn't innovative enough (yet no one is praising that in FIFA 16 you will be able to get right back up from a slide tackle challenge). But I'll stop here haha. Obviously I'm exaggerating and being a bit sarcastic in this post, but the moral of the story is that people just complain way too much in general and believe me, you will probably find a lot to complain about in PES 16. I still have a good time in FIFA and am never overwhelmed with "scripting"...then again I do have a special copy of FIFA 15 apparently!