You had all of those problems anyway.
G.Fast was given speed targets at various distances from 50m to 250m (150Mb @ 250m, 200Mb @ 200m, 500Mb @ 100m, 500Mb @ 50m with VDSL2 frequencies left alone, and allowing a Max of 1Gb @ 0m). It was never /just/ a 75m system.
The ITU had scenarios from multiple sides, not just BT, in setting those targets. Those problems needed solving and including in the specs.
The G.Fast targets ultimately reflect the realistic dreams of 5-8 years ago - that, if utterly lucky, copper could do gigabit. Just. Over the shortest of distances. But an aggregate of 150Mb at 250m is no better than vectored VDSL ... you just wouldn't target a multi-billion rollout to go just as fast as the previous rollout - which was a consideration to BT, but not all operators. The numbers say that a DP deployment was the only way to offer a jump in speeds for BT - so they probably saw it at the time as a 75m system more than anything else.
Nowadays the dreams are of 5Gbps over the shortest distances, and G.Fast has provided a framework that is far more capable than they ever expected. The extra capability now allows a significant jump in speed to be offered at distances of 200-250m, and a reasonable jump at distances of 300m-400m.
You might think of BT as having fiddled with the spec. However, if anyone realised what G.Fast would turn out to be capable of, those changes would have been in the original spec. I think, however, the telcos realised there was value in having V1 of the specs approved early, and that the changes could be best dealt with as subsequent amendments.
BT are, of course, one of the main drivers in research for G.Fast, so we should expect the standard to reflect and include their own requirements. But they're not alone ... and you can get a flavour of the research process from a Dutch perspective by looking at some of the documents here:
http://www.joepeesoft.com/Public/DSL_Corner/_Index.htmlThe presentations on 4GBB are interesting, but one of the more interesting is the "KPN requirements for G.Fast" - which shows a lot of the thought processes within KPN and and TNO with regard to deployment scenarios, and distances.
Swisscom are another example of an operator at the bleeding edge - where they are deploying their FTTS concept, with a range of 200m in mind.