You'll find that a lot of the ECI cabs were installed during the late 2012 to late 2013 period. Practically all cabs installed in 2013 were ECI's and by the end of the year I think the no of ECI's in use had practically caught up to the Huaweis which they'd been installing over the previous few years.
I dont know if its any co-incidence or not that this period coincides exactly to when there were substantial fears over Huawei using their DSLAMs for spying. iirc Australia banned any Huawei equipment in their broadband network after the CIA said they had found evidence of them doing this. Google it and you'll find loads of info to judge for yourself.
I don't know or not if it is true or not that they were and I don't want to contribute to myths & conspiracies, but could this be one of the contributing reasons why BT suddenly switched. BT also used to have a lot of Huawei stuff in their network, but a year or so ago they ordered and installed multiple hundreds of Alcatel kit. It could/would have been due for upgrade anyhow as they were redoing the MSE bRAS.. but one of those things that just make you wonder because I for one certainly wouldn't be surprised if at the time the likes of GCHQ weren't asking BT questions. Whatever the reason BT have always tended to use at least 2 different systems.
I believe what Openreach are trying to do is to have fibre closer to every home so that in the future running full fibre and FTTN, etc. is cheaper.
With full fibre they would have to run a line to each person which presumably would be more expensive than running it to one central point and then having multiple users order from that point.
I believe this too. In fact Ive seen it mentioned by BT boffins that FTTC isnt wasted. The major expense for BT (unlike B4RN) is the ducting and laying of fibre. FTTdp is an extension of FTTC which should fit in with existing equipment. Although expensive still much cheaper that FTTP. The final 100-200m is considered the most expensive part, particularly when it comes to return of investment.
In many respects it does make sense why they are doing it this way in steps because at least it means that speeds gradually increase. To do FTTP nationwide would take much longer.