I believe a lot of the fast pacing is accomplished in what I personally consider artificial means - shrinking maps and fast respawns. You basically spawn close enough to shoot or be shot within 5 seconds or less, or that seems to be the development philosophy.
There were some smallish maps in BF2, like Strike at Karkand. BF2142 was the beginning of linear map design. Under the BF2 style of gameplay, it worked just fine, since you didn't have spawning on every squad member as well as all vehicles. Luckily Back to Karkand on BF3 didn't have aircraft. As much as many might hate having a front line on a map, it does weed out the weak and tactically unsound from those who know how to take advantage of opportunity. Close in maps are not really the problem as long as they don't feature aircraft and are not dependent on linear design.
I do miss the focus on large open maps though. Gulf of Oman 2012/2014 is a great homage to what makes the original work so well.
Another issue with BF3 and 4 is the inability to damage aircraft and light vehicles with small arms, depending on some interesting factors. The 7.62mm helo and boat mounted miniguns and co-axial machine guns on tanks can damage small and light vehicles, but soldier carried 7.62 mm weapons do not. What I'm hoping is that future games at least give hit zones to vehicles. While a 5.56 or 7.62mm round into the wing may not do much (accept pierce an integral fuel tank), I certainly expect a shot directly into the engine to mean something. Modern combat helicopters do feature kevlar liners and armoring for vital components and crew from small arms (often up to cannon calibers), but fixed wing aircraft generally do not, and even still only to protect the crew only (A-10, Su-25).
So especially against rampant helicopters (especially little birds!), DICE needs to allow small arms to actually damage them, or beef up the damage caused by .50 cal/12.5/12.7mm and especially cannon rounds. Scout helicopters are just about invincible unless you manage to score it with an RPG round of which all the missiles and cannons are way too slow in velocity, IMMENSELY slow.
For AAA, there needs to be true to life ballistics, which would greatly increase the difficulty of using it against aircraft, but reward good AAA players by actually damaging aircraft and vehicles a more realistic amount. On the other hand, aircraft should be made faster. The short draw distances of BF2 and previous games are a thing of the past, so lining up for that crucial shot can be made from far out if need be.
I could go on and on, but I will digress..........