Slow moving enterprises in technology world are an age old phenomena. Even - long established, waterfall pattern following - enterprises are acknowledging this and speeding up their cycles. In the current world of fast pace technology, one cannot justify by giving such examples.
They probably could implement it much sooner, but they are waiting for 2 things (I'm speculating here).
1. Larger hashrate, which decreases likelihood of a 51% attack.
2. SegWit2x November hard fork.