Note though that detail wise fastlane still matches most mvm maps. Its underdetailed and not realy unique but still has a solid style. Any mvm map that uses the same looks will already be accepted.
The skybox part is the only bad thing, but in my entire time on fastlane i never noticed it being that way. And that still indicates a good capability to hide underdetailed areas. A skill which you should master in mvm.
My skybox in skullcove isnt realy that interesting either... I just did some things overly hard while it simply wasnt needed (the rocks in the background sew while you only see its borders and sewing simply wouldnt have mattered, and the water level matches the play area).
It simply is a poor skybox for a normal map, but since many probably havent noticed it being poor... it very likely is still acceptable. And best of all, it at least did an attempt at giving it a little bit of sense on why it stands there. You only see 2 pillars... but who knows if more are under it? There can still be more of them but they dont have to exist in the skybox. It could have been better but it isnt needed that much... people didnt notice it anyway.
In fact... things like those are far less of a problem than having the part under a staircase as nodraw (as pipeline had for years). As that does affect gameplay.
The gameplay of fastlane might be boring as hell, but its solid. Solid gameplay is still something that most mappers have problems with.
To me fastlane isnt the worst map though. Its gameplay might be boring, but at least its not anoying. That is still left to the map with poor clipping everywhere and a roof that is way too low (junction).