I thought mapgen week was fun, but would not want to see it done for a period longer then a week. The last day or two was a little tedious. That being said, would be excited to see it kick off the first 5 days of any month.
My two cents on the whole build whoring issue: What most people below 2k ladder think build whoring is, is just the other player having decent macro and a basic opener. That will not change regardless of if you play mapgen or not. I only know builds for a small handful of maps. Palms, badlands, and loki come to mind. The rest i just improvise on the spot.
A good build should make sure that you plan to build only as much power as you need, more mex/reclaim on map means more power, so plan ahead. Engis should expand quickly, and you should have an early tank or two screen for your expanding engis. Thats all there is to it. If you are wasting power (or god forbid, mass) in the first 5 minutes, thats not the result of a bad build, but of poor macro. That will be the same on mapgen or any custom map. Its a skill that needs to be developed.
Buildwhoring would be the tagada/nexus level creations. The secret badlands build, or any other build that requires you to have planned out engi reclaim/pathing to the absolute second, giving you a clear goal of a faster transport, bomber, or getting 2 factories ahead of your opponent by minute 5 due to cutting pgens or skipping mass extractors. It would be map specific, and have 0 power overflow with mass/energy storage at ~10% for the first 5 minutes.
If its something that can be done on any map, its not build whoring, its good macro. If its something that you can plan in the first 15 seconds by pulling up the reclaim field on the map and sending an engi to the nearest rock/wreck, its just good macro. If it truly was a build order whore, the player would be up in the land of 2k.
I say all of this not to antagonize or beat anyone down, but to help people try to understand how to better improve on their end. 90% of the people i train (or used to when i had more time), their biggest issues were their macro decisions. Not micro/gameplan choices. People up to 1600-1700 still spam t1 pgens in a line with 2-3 engis for the first 10 minutes, leaving their power management decided by the gods, regardless of the map. Once you have a decent understanding of the macro in this game, then you can start to learn how to really play it. Its really hard to outsmart people when they have 2-3x the stuff that you do. Its much easier to win when you have more tanks.