Every game is going to have ways players can go 40-3 in pubs. That's not a function of engine, or killstreak rewards (which were easily avoidable, besides maybe the human drivable ones at least in MW) or "sitting in a corner" with a sniper rifle (which if that's how someone is going 40-3 in a game you are in, I'd suggest getting a lot better). That's simply a function of players getting a lot better then 99% of the casuals that log into these games. I've played games with much larger battlefields then bf(#whatever) 10 years ago and that was true then as well. I've played games with smaller levels too. That has no impact on scores. People just get really really good at these games. If you've never played fps's with professional level players it's easy to blame this or that game mechanic and yes CoD killstreaks make it easy for good players to "pile it on" quicker. They are not the reason people get ridiculous scores in those games though. The "matchmaking" system is more to blame then anything IMO. It's easy to avoid servers where you are getting slaughtered if you have a choice. It's easy in games like CS for server administrators and their paid admin posies to clear out the people the rest of the server crys "hacks" on because they can pull off 15-1 kdrs but in games like modern warfare you just magically get sent to whatever host.
I played the beta of bf3 and I agree there are differences... I've never played the bf games before since ww2 shooters have never interested me so I had no reference point. The difference isn't really in engine which "new" is really just a marketing point for the gullible. They are updated for every new release of a game franchise and really aren't making leaps and bounds anymore because every large game is targeting old console hardware. The "engines" are mostly just window dressing anyways. The difference is in vehicle combat and map size. Both of which don't interest me personally in non-persistent worlds or games that try to do too many things, since I prefer my shooters to be bare even ground to out-skill people rather then trying to out rock-paper-scissors them, but to each their own.
I guess to this extent there are many things we disagree upon, then. I deeply disagree with the idea that a game's engine, design, flow and structure don't yield players to do better than others. Skill comes into play, without question. I have played professionally, Counter-Strike 1.6 to be specific, so I'm well aware of the differences between pub matches and skilled games. The issue is I
do believe Modern Warfare lends itself to give players a better chance of being better than they actually are. I've played against players I would call "good", and I've also played against players that I would call "game manipulators."
For example, I was never great at Modern Warfare 2. I had a k/d of 1.77, accuracy of about 20%, etc. Some maps I would generally average about as many kills as deaths. There were other maps, however, where I had learned exactly where I could go and exactly what to do in order to get easy kills, hike up my score, get a lot of killstreaks, and dominate the game. Didn't matter who was on the other team - I'd play really well. Certain rooms that were near impenetrable, areas where people never looked, etc. I don't disagree with the idea that people just get better at the game, but to say that a game's design has absolutely "no" effect on a score is drastically incorrect. It has an effect to a certain extent, as I have mentioned in this paragraph.
Lastly, there are significant differences between the graphics for both of these games. It doesn't matter how many times you update an engine for each new installment, because there will always be a new engine that performs better than the previous old and updated engine. There will
always be limitations with an engine, just like there are
always limitations with certain computers. BF3 is using a new engine that outperforms and outclasses MW3. If I can find the article that talks about it, I will link it in this page.
MW2 came out years after BF2 did, but the performance and detail of the engine used to create BF3 puts the MW3 game to shame, and I think saying the only difference between these games is vehicle and map size only scratches the surface of how these games are different. Overall, both of these games offer different multiplayer experiences, so it really comes down to personal preference. I believe Battlefield just does a better job, and that they put more effort into their games.