with a few rare exceptions like the breakfast club and dueling league. At least there were no Yak3s back then... 
Yeah awesome. That's where I lived. Having more than one practical arena means you can always move about if one becomes a bit lame. It's not so now. Players just log off. Some stop subscribing.
I just wish there were more 1v1 aficionados nowadays.
Speaking only for myself (CET player), I've been driven away (or my hobby made inaccessible if you like, which amoounts to the same thing) because in the MA presently available to me any amount of hard-earned skill can trivially be countered by exploiting the arena and not the ACM-plane-player combination. As an example there's a couple of (well a pair actually) players who absolutely refuse any kind of even fight and will burn 5k of energy in a shallow dive to escape even a less-manouvrable plane if it isn't a convincingly safe engagement for them. They'll be promptly back if you engage someone else though.
One of these was a consistent MPA dueller. After a long break I fought him regularly for a month losing a high percentage of fights against his Spit9. Right up until the point I found a reliable method to defeart him. After a something like 10 out of 12 defeats ratio he started ducking me in the MPA too. That's a snapshot of differing philosophies and goals right there. Apply these incompatible philosophies over time without some kind of balancing system and...
The ELO is a good system for something long-standing like a chess competition. But in the MPA if you have a high ELO and get defeated even by proxy by a lower-scored player it costs you a lot and takes ages to get back. Your rating can plummet in minutes. Same system for both AI and human players. The upshot of that is, again, to discourage gameplay in those whom are unable to ignore score or even to have score used as a peeny-comparison tool (I noticed a week or so ago on the forum, lol).
A better system might be some reward-based system where if you don't fight at a reasonable rate then your ELO degrades automatically. That's what essentially happpens in some other sports.
Anyway, all sorts of things could be done. If there's an inherent unwillingness to make a simple concession like unlocking three airbases then it's just idle chatting around the coffee apparaat.