Well, that'd require OpenSim to have an official "centre" to start with. What'd that be? OSgrid? A hypothetical new grid started by the main devs so it comes from the same hands as OpenSim itself?
If the OSgrid can be seen as the "centre" of OpenSim, then Wright Plaza would be what you've described, but Wright Plaza is fully booked AFAIK.
The idea itself sounds very good. Social Mouse is still reworking her grid to only contain legal content, and this will include shops, so she may offer shops to creators to have more than just Linda Kellie, Selea Core, Hylee Bekkers or what else I've pointed her at. Zoe Synclair may still have vacancies at Uzuri (
https://opensimworld.com/hop/86638) which has a similar goal, but limited to that one sim. None of these wil be any more central than Wright Plaza, though.
Also, if OpenSim creators started to flock into such a place, it'd fill up quickly, so it'd have to be huge. It'd have to be even bigger if the sim owner added shops with items made by long-inactive creators or by creators who allow third parties to run shops with their content (a Ruth&Roth shop, a Selea Core shop, a Hylee Bekkers shop although there is one at Wright Plaza, an Arcadia Asylum/Aley Arai shop etc.)
What do you mean with "newer type"? "Wright Plaza, but the buildings are modern mesh" = "RRD Fashion Exclusives, but with more than one shopkeep"?
Speaking of Wright Plaza, maybe it'd be a good idea to turn it into a varsim to have more shop space. I think it has been around since before varsims were possible. Or maybe build an adjacent Wright Plaza II with the same buildings.