also was it because of the Lumia acquisition made it hard to push a "Flagship" phone everyone moans about?
No. It's really two issues:
1) Nokia/MS has hard data that flagship WP doesn't sell - so why put divert limited resources into the high end when they have a big shake up next year? Why NOT use the resources smartly and invest in the low end first, THEN release a high end next year when Win10 comes out?
2) The flagship which MS could realistically release this year had to be what Nokia had in the pipeline, yet Nokia obviously made quite a few lemon phones in the final years before the acquisition. Namely the crappy 530 follow up to the 520, the 830 which while nice was too pricey, and finally the McLaren/1030 which was focusing on a 3D gesture feature which developers found no use for AND it wasn't going to be the true 1020 successors people want anyway (as reported by Tom Warren it has a 20MP shooter, not a 41MP one, and the leaked prototype shows that it doesn't even have a mechanical shutter and Xeon flash, which are all features which made the 1020 great). MS was absolutely right to cancel that abomination which would no doubt flop really badly, and arguably if they did not only would they loss good faith but lots of money as well, compared to now which is they **** off some hardcore fans, the choice was easy.
Actually now come to think of it something was definitely off at Nokia in 2012/2013 when prototypes and strategy for the X30 Lumias were being developed. Compared to the X20 series it seems they've completely lost the plot as devices were compromised in strange ways. And yes this fault lies squarely with Nokia and not MS as this is way before the acquisition.