Some servers for BF2 and BF 2142 enforce this policy with a squad less kick script.
For example: Tactical Gamer

Usually i noticed on this servers a better Teamplay.

Let's face it:
Even without giving orders a squads fight effective if the players stick around the Squadleader and follow him when he charge in battle.

With orders, the Squadmembers can lead the assault and the Leader is following, this means the squad fights even more effective.

On the other side: If the squad don't stick with the leader and don't follow orders all squadmembers fight ineffective (except the enemy also don't fight in a squad).

I kick Players from the Squad and invite new members if they don't follow orders and don't stick with me. On a server with kickscript this can cause them to get kicked from the server (if they don't find an other squad where they don't get kicked).
IMHO this is a good way to get non teamplaying players from the server.

IMHO the Squadless kick Script for BF2 should work with BF 2142 too.

IMHO this script should be part of the packet, but it's use should be desicion of the server admin.

Talking about squads:
It's sad to say what DICE didn't build all features into the Squadsystem they thought about.

In the BF 2142 Sound_client.zip many VO who could be helpfull to make the Squadsystem better are unused.
Like
COMMSL_SQUAD_assignedsl.ogg ->"You are now the leader of your squad"
COMMSL_SQUAD_newslassigned_alt.ogg ->"Your squad have a new leader"
Would be very helpfull if the old Squadleader has left the server.

PLAYER_TACTICS_SL_gather.ogg ->"Gather around me"
Would help to coordinate assaulst better.

The Squadsystem of BF 2142 and the CommoRoses are IMHO two great tool of BF what acctually help to get better Teamplay.

CYNIC, n. A blackguard whose faulty vision sees things as they are, not as they ought to be. Hence the custom among the Scythians of plucking out a cynic’s eyes to improve his vision

On the one hand, I'm very much in favor of squad work and I think it's a good idea. On the other hand, it will lead to non-teamwork squads which people join "just to join them". I also feel, however, that this shouldn't be that big a problem for the people who want teamwork, simply because squads with names like "Strategy" or "Teamwork" attract people more than squads with generic names.

Biggest issue is that FS attracts arcade players. This is an argument against this implementation, in that they'd dislike it, but in my eyes it's just as much an argument for it as I think, as Ty says, that we should set the bar higher and attract more teamwork-oriented players.

If this system is not implemented, at least implement a system that means you get more points when in a squad.
Not in squad: Score reduced by 25%.
In squad: Score at 100%.
Squad leader with officer kit: Score increased by 10%.

Something like that. Don't look at it as punishing players - look at it as rewarding those who perform.
Then again, was this a realism mod, I'd make it so that you got no points when not in a squad.

Do what Project Reality has done in the Insurgency maps, which have status messages which read something like "The insurgency has x caches left in the area. Search the area and destroy at least y of them". These messages are shown in big fonts and can't be missed. So either make the "Warning: Player #PLAYERNAME# has x seconds to join a squad before being auto-kicked" messages show in large fonts, or in red fonts, or something like that.

And yet when we do implement rules, hardly anyone complains. I've said this before - how many people have complained about Push mode? Or limiting weapons and devices to people in squads? Or the force field making it impossible to enter the ISD Hangar for the Rebels?

There's nothing wrong with restricting the players' actions if it improves the mod experience.

I so wholeheartedly agree. I've repeatedly found myself SL without warning, and it's very annoying. Devs, is there a way to make this sound or voice line (when we get voice actors) play when you become squad leader, instead of just a nondescript message I miss 90% of the time?