Yes, I concur. Tons of players play no-event, all build menu buildings. I don't get it, but it's the way they want to play. I saw a guy's city in Titan, and it had a level 54 Arc.... lol.
Inno only tells us WE MUST negotiate GE encounters for Rival or quests, or fight consecutive battles without a loss, but you don't ever have to play an event to be a legitimate FoE player and can surely - DO IT YOUR WAY when it comes to how you want your city to be constructed.
I can confirm this... to an even greater extent. I've experimented with my main live city and Beta city in parallel. My main city was (still is) focussed on events, while my Beta city has been tasked to try to play as vanilla as possible. Even minimising GB's. It's very difficult as most regular buildings efficiency isn't matching demands well ever since SA:V/SA:JM. Up to VF it can offer some fun as up to that age vanilla buildings have a nice style to them. From SA:M it's pretty much over, all love goes into the colony and even those don't see typically not much back from it.
Ok. So (1) what would you put into the research if you want no city buildings? (2) what’s your plan for completing event quests?
I can't answer on behalf of someone else but I'm intrigued by the question. So, I'd like to answer. The roads for the main city remain useful until MTG decides to make all future event buildings roadless to boost effective usable city space for selling event buildings. So, they'll stay. Quests for houses can be satisfied through the colony's houses. So, they can be cut first. Other buildings momentarily not: cultural; decorations; military buildings. If MTG decides for Inno that in the future colonies run on colony produced resources (coins, supplies) only and with only the starter buildings like houses and production buildings with maybe goods buildings there's not much to be cut from the TT. Even if it does happens, cultural and decoration buildings probably have to stay for quests.
So, to summarise: every main city building type that can be build in the space colony
That been said, the underlaying question could be more fundamental: why are main city buildings so unpopular? The simple reality is that they're outdone by a land slide by event buildings. The OG/old devs probs foresaw this when developing PME. Spicing up vanilla buildings with bonuses: (negative) happiness to production buildings and military buffs to production buildings. This has been dropped entirely with SA:M. I think however they had a decent vision with it. When contemporary era was released a few highly competitive players filled their cities with light units buildings to massively buff their attack %. Yes 4%/building with large population requirements. Event buildings where not that common or powerful back than. Case in point if vanilla buildings are getting buffed with somewhat efficient bonuses but still be outdone by let's say 50%+ in terms of efficiency by event and special buildings. Alongside a small-ish footprint (3x3 max for production buildings, 4x4 max for cultural buildings) I think they might feel less as a waste for research slots. As they could be seen as okay-ish disposable buildings for events w/o sacrificing space that could've been used for military buffs or fp production.