The strength of BF is variety. That's what always kept me coming back. And not variety of assault rifles. But variety of roles to play in combination with a variety of maps in Conquest. Not only the classes but being a pilot, shooting at planes form AA, driving a tank, using the apcs, captaining a ship or even sub, firing the big guns at ships, using stationary mgs. mining, repairing, rpg'ing tanks, etc. And the variety of maps changed how these roles played out or which ones were available even. And this variety was in service of the objectives and trying to win the round.
I would always switch up my role to not only help the team but to keep the game fresh. And I never got bored as a rule of thumb.
The expansion packs delivered fresh content within 6-9 months that had great uniqueness and focus and completeness. The ones I remember were Road To Rome. SEcret WEapons of WW2. And Special Forces.
IN my experience, today's BF homework makes the game less fun to play because so many are focused on checking off boxes and often ignoring the threats in front of their eyes and the objectives in service of the progression.
It might keep them coming back, but ...I don't think they get to like the game for the game. And it makes my experience less fun. I liken it to playing football with 10 others who are busying trying to check off the week's homework assignments while on the field during a game.
Why is CoD bigger than BF? Been asked many times, but BF is too complicated for the average player. Also CoD was more of a console game after the first one especially. And console games were bigger then. And then Activision kept those games coming every year.
CoD has a small player count and is only focused on guns and the base mode is just kill the other guys. Simple like Counter STrike. That just has a larger user base. It's the lowest common denominator. Like top 40 music.
Another way to think about it is the strength of BF is what keeps it from being as big. The main mode is objective based. To this day, most people don't really know how to play the mode. They play musical flags instead. And then flying or countering planes is foreign to them. Tanks are too powerful in their minds. Etc.
There was also always a little more patience needed in BF especially in old BF games. Patience to get back in after dying. Patience to get around the map in general. Patience to give or get a ride. Patience to wait 30 seconds for the enemy to come back. Patience to not just run off after getting a flag but look around for enemies and slowly expand the front. Not conducive to the average yahoo in general.