But then you get an entirely new and surprising goop of problems like bursty lag problems (one out of 500 requests finishes in 5s instead of 0.1s), lack of consistency because one of the datacenters is offline, and so many others.

It's more like "you now have to deal with different problems" much more than it is "you have to deal with less problems". Maybe the problem quantity got reduced from 1000+ to 50+ but the latter might swallow much more time to solve so it's really questionable which of both is better.