What if there was a game mode primarily based on strategic actions rather than tactical ones? It could only be for major planets, so we could call it Capital Mode. Like, imagine...
Tukayyid, or one of the other major planets. Say Clan Ghost Bear players organize a major offensive at the Draconis Combine and manage to reach Luthien. Then they assault it.
I think it would be a great disservice to such a monumental invasion to let it just be "You have 24 hours to get as many wins as possible, GO!", which is the same set of rules for any other planet.
Instead, players are selected for their excellent command abilities--you could integrate MechWarrior Tactics here! Link the accounts, and if your account in MWT is highly ranked enough you might get the opportunity to do this in MWO!--and face off as regiment commanders on the planet's surface. Every day, they make decisions about where to move various units, which places to defend, attack, etc. Maybe send a mercenary corp on a recon mission while holding on to your house troops to defend your base. That sort of thing.
Meanwhile, the attacker is doing the same thing, trying to probe over the course of many days where troops are hidden, while sieging various important facilities, laying ambushes on bridges, etc.
And every time two units meet in armed combat, _THAT COMBAT_ is performed by the associated MWO community factions. So when a Ghost Bear recon Star accidentally bumps into a Draconis Combine recon company (and keep in mind, in BattleTech, a five-man Clan Star is MORE than a match for a 12-man IS company), suddenly hundreds of players are given the option to queue up for playing that battle out.
At the end of several days, if the attacker has failed to take the planet, he automatically retreats/the planet receives reinforcements.
...
This mode could have a huge number of other features to it too. Like, limited resources/repair times... maybe people queuing up for the combat are forced into whatever 'Mechs were actually fighting in that battle... and of course, BEST feature: this several-day battle for a regional/national capital planet would be broadcast to EVERYONE! Everyone could check in to see whether the Luthien regiments are holding off the clans, or whether ComStar is holding its own against the Clans on Tukayyid...
People would be participating in the battles themselves, of course, but the extra level of excitement would come from seeing the war effort for that one MAJOR planet shift over the course of several days... losing and gaining ground... troop movements..
I think it could work. If would greatly add to MechWarrior Online I think: most games tend to have "events" now and then, limited-time achievements or maps or whatever, to help spice up the regularity of the game. Well, this not only would supplement MWO's "events", but it would do it automatically, without the devs having to arrange anything (except programming the mode to begin with of course

Anyway. Just my random thoughts. If that was in the game, you can bet I'd be playing like Hell whenever one of the major planets in _MY_ nation came under attack..