You could hold the first part of your statement true for every game that has ever had a number after it, within reason every game after the first one at its core only does those very things, BF2142 was using the same engine that BF2 did & that was a full priced game, everything could have been done as DLC. Was that ok, but this is not?
Battlefront will be just like Battlefront but with better graphics, new weapons, new maps & new UI, the format is still the same
I didn't own any old BF game (didn't have my own gaming PC, just consoles), only played on friend's pc's etc. for like a few hours so can't really give my opinion regarding those two and besides that was so long ago, I can't even remember the game that well!
But if the core of the game and everything that made it tick was the
exact same, the mechanics, animations etc. and it was just a "reskin" with different vehicles etc. then yes I would say there is no need for a completely new separate game then.
Now what I would consider to be a
true new game is something like when comparing Batman Arkham Asylum and city for these reasons:
- it was just running on an updated engine iirc, however, the graphics were much improved in every area, sounds were improved, better animations etc.
- the gameplay mechanics were a lot better, the flight, combat, scale of map etc.
- new gadgets and improved the way the older ones worked
- much improved UI/map that was interlinked with some parts of the game missions
- way more challenge stuff
And then the usual stuff like new environment, completely new story, characters etc.
Pretty much every single thing was vastly improved over the first and this was all done on more or less the same engine. So yes, perhaps they could have just released this as a DLC pack and included everything via a patch but when so much has changed, then a new game is needed, that is my point regarding these new videos of BF 4, apart from a few small changes, the biggest thing being related to the map, "so far" it just looks/acts/performs the same as the "core" of BF 3 imo.
In all honesty, if they didn't mention BF 4 or anything at all about that video, I would have thought that was the next DLC pack for bf 3 where as when watching the early trailers for B:AC, it looked like a different game overall.
I don't really care if companies use the same engine (how many games use the same unreal engine???), as long as they improve everything about the game and make it stand out from the previous game then I am happy with that.
As I said many times before though, I am just basing this on what I have seen "so far" (and things could be very different considering this isn't final), my opinion could/will change once we see more of the gameplay mechanics and that will be the decider for me as to if I look at BF 4 as just an "expansion pack" for BF 3 or a "new" game.
TBH, if it is just like battlefront 1 and 2 but with updated graphics, sounds, animations, weapons etc. then I will be very happy where as if it is just BF 3/4 reskinned i.e. same core mechanics but different vehicles etc. then I'll be slightly disappointed as my problem with BF 3 isn't related to the engine, graphics etc. but with the "gameplay mechanics" i.e. things like poor balance between vehicle and infantry, poor map design, land slide wins etc. (imo)
)
Orginal Call of Duty + United Offensive,Battlefield 1942 and RTCW:ET on the new engines would suit me fine 
